Bring back gc() function

Renaming gc() to _gc() was a mistake since the better thing to do is put
it behind the _COSMO_SOURCE macro. We need this change because I haven't
wanted to use my amazing garbage collector ever since we renamed it. You
now need to define _COSMO_SOURCE yourself when using amalgamation header
and cosmocc users need to pass the -mcosmo flag to get the gc() function

Some other issues relating to cancelation have been fixed along the way.
We're also now putting cosmocc in a folder named `.cosmocc` so it can be
more safely excluded by grep --exclude-dir=.cosmocc --exclude-dir=o etc.

test/net/http/decodebase64_test.c

@@ -16,7 +16,7 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
-#include "libc/mem/gc.internal.h"
+#include "libc/mem/gc.h"
 #include "libc/str/str.h"
 #include "libc/testlib/testlib.h"
 #include "net/http/escape.h"

test/net/http/decodelatin1_test.c

@@ -18,7 +18,7 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/errno.h"
 #include "libc/mem/mem.h"
-#include "libc/mem/gc.internal.h"
+#include "libc/mem/gc.h"
 #include "libc/str/str.h"
 #include "libc/testlib/ezbench.h"
 #include "libc/testlib/hyperion.h"

test/net/http/encodebase64_test.c

@@ -16,7 +16,7 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
-#include "libc/mem/gc.internal.h"
+#include "libc/mem/gc.h"
 #include "libc/mem/mem.h"
 #include "libc/stdio/rand.h"
 #include "libc/str/str.h"

test/net/http/encodehttpheadervalue_test.c

@@ -18,7 +18,7 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/errno.h"
 #include "libc/mem/mem.h"
-#include "libc/mem/gc.internal.h"
+#include "libc/mem/gc.h"
 #include "libc/stdio/stdio.h"
 #include "libc/str/str.h"
 #include "libc/testlib/ezbench.h"

test/net/http/escapehtml_test.c

@@ -17,7 +17,7 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/mem/mem.h"
-#include "libc/mem/gc.internal.h"
+#include "libc/mem/gc.h"
 #include "libc/str/str.h"
 #include "libc/testlib/ezbench.h"
 #include "libc/testlib/hyperion.h"

test/net/http/escapejsstringliteral_test.c

@@ -19,7 +19,7 @@
 #include "libc/calls/calls.h"
 #include "libc/log/check.h"
 #include "libc/mem/mem.h"
-#include "libc/mem/gc.internal.h"
+#include "libc/mem/gc.h"
 #include "libc/stdio/stdio.h"
 #include "libc/temp.h"
 #include "libc/str/str.h"

test/net/http/escapeurlparam_test.c

@@ -17,7 +17,7 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/mem/mem.h"
-#include "libc/mem/gc.internal.h"
+#include "libc/mem/gc.h"
 #include "libc/str/str.h"
 #include "libc/testlib/ezbench.h"
 #include "libc/testlib/hyperion.h"

test/net/http/indentlines_test.c

@@ -17,7 +17,7 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/mem/mem.h"
-#include "libc/mem/gc.internal.h"
+#include "libc/mem/gc.h"
 #include "libc/str/str.h"
 #include "libc/testlib/ezbench.h"
 #include "libc/testlib/hyperion.h"

test/net/http/isacceptablepath_test.c

@@ -16,7 +16,7 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
-#include "libc/mem/gc.internal.h"
+#include "libc/mem/gc.h"
 #include "libc/testlib/ezbench.h"
 #include "libc/testlib/testlib.h"
 #include "net/http/escape.h"

test/net/http/parsehttpmessage_test.c

@@ -18,7 +18,7 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/errno.h"
 #include "libc/log/check.h"
-#include "libc/mem/gc.internal.h"
+#include "libc/mem/gc.h"
 #include "libc/mem/mem.h"
 #include "libc/str/str.h"
 #include "libc/testlib/ezbench.h"

test/net/http/parseurl_test.c

@@ -17,7 +17,7 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/limits.h"
-#include "libc/mem/gc.internal.h"
+#include "libc/mem/gc.h"
 #include "libc/mem/mem.h"
 #include "libc/stdio/rand.h"
 #include "libc/str/str.h"

test/net/http/underlong_test.c

@@ -17,7 +17,7 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/mem/mem.h"
-#include "libc/mem/gc.internal.h"
+#include "libc/mem/gc.h"
 #include "libc/testlib/ezbench.h"
 #include "libc/testlib/hyperion.h"
 #include "libc/testlib/testlib.h"

test/net/http/visualizecontrolcodes_test.c

@@ -26,26 +26,26 @@
 
 TEST(VisualizeControlCodes, test) {
   size_t n;
-  EXPECT_STREQ("hello", _gc(VisualizeControlCodes("hello", -1, 0)));
-  EXPECT_STREQ("hello\r\n", _gc(VisualizeControlCodes("hello\r\n", -1, 0)));
-  EXPECT_STREQ("hello␁␂␡", _gc(VisualizeControlCodes("hello\1\2\177", -1, 0)));
+  EXPECT_STREQ("hello", gc(VisualizeControlCodes("hello", -1, 0)));
+  EXPECT_STREQ("hello\r\n", gc(VisualizeControlCodes("hello\r\n", -1, 0)));
+  EXPECT_STREQ("hello␁␂␡", gc(VisualizeControlCodes("hello\1\2\177", -1, 0)));
   EXPECT_STREQ("hello\\u0085",
-               _gc(VisualizeControlCodes("hello\302\205", -1, 0)));
-  EXPECT_STREQ("hi", _gc(VisualizeControlCodes("hi", -1, &n)));
+               gc(VisualizeControlCodes("hello\302\205", -1, 0)));
+  EXPECT_STREQ("hi", gc(VisualizeControlCodes("hi", -1, &n)));
   EXPECT_EQ(2, n);
 }
 
 TEST(VisualizeControlCodes, testOom_returnsNullAndSetsSizeToZero) {
   size_t n = 31337;
-  EXPECT_EQ(NULL, _gc(VisualizeControlCodes("hello", 0x1000000000000, &n)));
+  EXPECT_EQ(NULL, gc(VisualizeControlCodes("hello", 0x1000000000000, &n)));
   EXPECT_EQ(0, n);
 }
 
 TEST(VisualizeControlCodes, testWeirdHttp) {
   size_t n = 31337;
   char *p, B[] = "\0GET /redbean.lua\n\n";
-  ASSERT_NE(0, (p = _gc(VisualizeControlCodes(B, sizeof(B), &n))));
-  EXPECT_STREQ("\"␀GET /redbean.lua\\n\\n␀\"", _gc(xasprintf("%`'.*s", n, p)));
+  ASSERT_NE(0, (p = gc(VisualizeControlCodes(B, sizeof(B), &n))));
+  EXPECT_STREQ("\"␀GET /redbean.lua\\n\\n␀\"", gc(xasprintf("%`'.*s", n, p)));
 }
 
 BENCH(VisualizeControlCodes, bench) {