Get threads working well on MacOS Arm64

- Now using 10x better GCD semaphores
- We now generate Linux-like thread ids
- We now use fast system clock / sleep libraries
- The APE M1 loader now generates Linux-like stacks

third_party/nsync/mu_semaphore_futex.c

@@ -23,13 +23,12 @@
 #include "third_party/nsync/atomic.internal.h"
 #include "third_party/nsync/futex.internal.h"
 #include "third_party/nsync/mu_semaphore.internal.h"
-
-asm(".ident\t\"\\n\\n\
-*NSYNC (Apache 2.0)\\n\
-Copyright 2016 Google, Inc.\\n\
-https://github.com/google/nsync\"");
 // clang-format off
 
+/**
+ * @fileoverview Semaphores w/ Linux Futexes API.
+ */
+
 #define ASSERT(x) _npassert(x)
 
 /* Check that atomic operations on nsync_atomic_uint32_ can be applied to int. */