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/kmalloc.h

@@ -5,6 +5,9 @@ COSMOPOLITAN_C_START_
 
 void *kmalloc(size_t) mallocesque attributeallocsize((1)) returnsaligned((8));
 
+void __kmalloc_lock(void);
+void __kmalloc_unlock(void);
+
 COSMOPOLITAN_C_END_
 #endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
 #endif /* COSMOPOLITAN_LIBC_INTRIN_KMALLOC_H_ */