Make more threading improvements

- ASAN memory morgue is now lockless
- Make C11 atomics header more portable
- Rewrote pthread keys support to be lockless
- Simplify Python's unicode table unpacking code
- Make crash report write(2) closer to being atomic
- Make it possible to strace/ftrace a single thread
- ASAN now checks nul-terminated strings fast and properly
- Windows fork() now restores TLS memory of calling thread

libc/intrin/stracef.greg.c

@@ -19,10 +19,13 @@
 #include "libc/intrin/kprintf.h"
 #include "libc/intrin/strace.internal.h"
 #include "libc/runtime/runtime.h"
+#include "libc/thread/tls.h"
 
 privileged void __stracef(const char *fmt, ...) {
   va_list v;
-  if (__strace <= 0) return;
+  if (__strace <= 0 || (__tls_enabled && __get_tls()->tib_strace <= 0)) {
+    return;
+  }
   va_start(v, fmt);
   kvprintf(fmt, v);
   va_end(v);