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.

tool/viz/lib/bilinearscale.c

@@ -86,12 +86,12 @@ void *BilinearScale(long dcw, long dyw, long dxw,
       DCHECK_LT(_bsrl(cn) + _bsrl(dyn) + _bsrl(dxn), 32);
       BilinearScaler(dcw, dyw, dxw, dst, scw, syw, sxw, src, c0, cn, dyn, dxn,
                      syn, sxn, ry, rx, oy, ox,
-                     _gc(xmemalign(64, ROUNDUP(sizeof(int) * (dyn + 1), 64))),
-                     _gc(xmemalign(64, ROUNDUP(dyn + 1, 64))),
-                     _gc(xmemalign(64, ROUNDUP(sizeof(int) * (dxn + 1), 64))),
-                     _gc(xmemalign(64, ROUNDUP(dxn + 1, 64))),
-                     _gc(xmemalign(64, ROUNDUP(dxn, 64))),
-                     _gc(xmemalign(64, ROUNDUP(sxn, 64) * 2)));
+                     gc(xmemalign(64, ROUNDUP(sizeof(int) * (dyn + 1), 64))),
+                     gc(xmemalign(64, ROUNDUP(dyn + 1, 64))),
+                     gc(xmemalign(64, ROUNDUP(sizeof(int) * (dxn + 1), 64))),
+                     gc(xmemalign(64, ROUNDUP(dxn + 1, 64))),
+                     gc(xmemalign(64, ROUNDUP(dxn, 64))),
+                     gc(xmemalign(64, ROUNDUP(sxn, 64) * 2)));
     } else {
       bzero(dst[c0], &dst[cn][0][0] - &dst[c0][0][0]);
     }

tool/viz/lib/dither.c

@@ -22,7 +22,7 @@
 #include "libc/log/log.h"
 #include "libc/macros.internal.h"
 #include "libc/math.h"
-#include "libc/mem/gc.internal.h"
+#include "libc/mem/gc.h"
 #include "libc/mem/mem.h"
 #include "libc/str/str.h"
 #include "tool/viz/lib/graphic.h"

tool/viz/lib/formatmatrix-byte.c

@@ -18,8 +18,8 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/assert.h"
 #include "libc/math.h"
-#include "libc/mem/mem.h"
 #include "libc/mem/gc.h"
+#include "libc/mem/mem.h"
 #include "libc/x/xasprintf.h"
 #include "tool/viz/lib/formatstringtable.h"
 #include "tool/viz/lib/stringbuilder.h"
@@ -44,7 +44,7 @@ void FormatMatrixByte(long yn, long xn, const unsigned char M[yn][xn],
       yn, xn,
       formatter(yn, xn,
                 ConvertByteMatrixToStringTable(
-                    yn, xn, _gc(calloc(yn * xn, sizeof(char *))), M),
+                    yn, xn, gc(calloc(yn * xn, sizeof(char *))), M),
                 emit, arg, param1, param2, param3));
 }
 

tool/viz/lib/formatmatrix-double.c

@@ -20,7 +20,7 @@
 #include "libc/fmt/conv.h"
 #include "libc/log/check.h"
 #include "libc/math.h"
-#include "libc/mem/gc.internal.h"
+#include "libc/mem/gc.h"
 #include "libc/mem/mem.h"
 #include "libc/x/x.h"
 #include "third_party/gdtoa/gdtoa.h"

tool/viz/lib/formatmatrix-float.c

@@ -17,7 +17,7 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/math.h"
-#include "libc/mem/gc.internal.h"
+#include "libc/mem/gc.h"
 #include "libc/x/x.h"
 #include "tool/viz/lib/formatstringtable.h"
 

tool/viz/lib/formatmatrix-short.c

@@ -18,8 +18,8 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/assert.h"
 #include "libc/math.h"
-#include "libc/mem/mem.h"
 #include "libc/mem/gc.h"
+#include "libc/mem/mem.h"
 #include "libc/x/x.h"
 #include "libc/x/xasprintf.h"
 #include "tool/viz/lib/formatstringtable.h"
@@ -45,7 +45,7 @@ void FormatMatrixShort(long yn, long xn, const short M[yn][xn], int emit(),
       yn, xn,
       formatter(yn, xn,
                 ConvertShortMatrixToStringTable(
-                    yn, xn, _gc(xcalloc(yn * xn, sizeof(char *))), M),
+                    yn, xn, gc(xcalloc(yn * xn, sizeof(char *))), M),
                 emit, arg, param1, param2, param3));
 }
 

tool/viz/lib/formatstringtable-assembly.c

@@ -18,7 +18,7 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/fmt/itoa.h"
 #include "libc/intrin/safemacros.internal.h"
-#include "libc/mem/gc.internal.h"
+#include "libc/mem/gc.h"
 #include "libc/str/str.h"
 #include "libc/str/strwidth.h"
 #include "libc/x/x.h"

tool/viz/lib/ycbcr2rgb3.c

@@ -35,7 +35,7 @@
 #include "libc/log/log.h"
 #include "libc/macros.internal.h"
 #include "libc/math.h"
-#include "libc/mem/gc.internal.h"
+#include "libc/mem/gc.h"
 #include "libc/mem/mem.h"
 #include "libc/nexgen32e/gc.internal.h"
 #include "libc/nexgen32e/nexgen32e.h"