Make garbage collection thread safe

- You can now use _gc(malloc()) in multithreaded programs
- This change fixes a bug where fork() on NT disabled TLS
- Fixed TLS code morphing on XNU/NT, for R8-R15 registers

test/libc/sock/sendrecvmsg_test.c

@@ -17,6 +17,7 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/assert.h"
+#include "libc/calls/calls.h"
 #include "libc/calls/struct/iovec.h"
 #include "libc/dce.h"
 #include "libc/errno.h"

test/libc/sock/test.mk

@@ -34,6 +34,7 @@ TEST_LIBC_SOCK_DIRECTDEPS =					\
 	LIBC_STR						\
 	LIBC_STUBS						\
 	LIBC_SYSV						\
+	LIBC_LOG						\
 	LIBC_SYSV_CALLS						\
 	LIBC_TESTLIB						\
 	LIBC_X							\