Fix breakages in Linux-only build modes

- compile.com now polyfills -march=native which gcc/clang removed
- Guarantee zero Windows code is linked into non-Windows binaries
- MODE=tinylinux binaries are now back to being as tiny as ~4kb
- Improve the runtime's stack allocation / alignment hack
- GitHub Actions now tests Linux modes for assurance

test/libc/calls/mkntpath_test.c

@@ -18,8 +18,10 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/calls/internal.h"
 #include "libc/calls/syscall_support-nt.internal.h"
+#include "libc/dce.h"
 #include "libc/mem/gc.internal.h"
 #include "libc/testlib/testlib.h"
+#if SupportsWindows()
 
 char16_t p[PATH_MAX];
 
@@ -48,3 +50,5 @@ TEST(mkntpath, testRemoveDoubleSlash) {
   EXPECT_EQ(21, __mkntpath("C:\\Users\\jart\\\\.config", p));
   EXPECT_STREQ(u"C:\\Users\\jart\\.config", p);
 }
+
+#endif /* SupportsWindows() */

test/libc/thread/pthread_setname_np_test.c

@@ -100,13 +100,14 @@ TEST(pthread_setname_np, GetNameOfOtherThread) {
   ASSERT_EQ(0, pthread_create(&id, 0, GetNameOfOtherThreadWorker, 0));
   while (!atomic_load(&sync1)) pthread_yield();
   errno_t e = pthread_getname_np(id, me, sizeof(me));
-  if (IsLinux() && e == ENOENT) return;  // bah old kernel
-  if (IsLinux() && e == EACCES) return;  // meh landlock
+  if (IsLinux() && e == ENOENT) goto GiveUp;  // bah old kernel
+  if (IsLinux() && e == EACCES) goto GiveUp;  // meh landlock
   ASSERT_EQ(0, e);
   EXPECT_STREQ("justine", me);
   ASSERT_EQ(0, pthread_setname_np(id, "tunney"));
   ASSERT_EQ(0, pthread_getname_np(id, me, sizeof(me)));
   EXPECT_STREQ("tunney", me);
+GiveUp:
   atomic_store(&sync2, 1);
   ASSERT_EQ(0, pthread_join(id, 0));
 }