Apply even more fixups

- Finish cleaning up the stdio unlocked APIs
- Make __cxa_finalize() properly thread safe
- Don't log locks if threads aren't being used
- Add some more mutex guards to places using _mmi
- Specific lock names now appear in the --ftrace logs
- Fix mkdeps.com generating invalid Makefiles sometimes
- Simplify and fix bugs in the test runner infrastructure
- Fix issue where sometimes some functions wouldn't be logged

libc/log/backtrace.internal.h

@@ -7,6 +7,7 @@
 COSMOPOLITAN_C_START_
 
 forceinline pureconst bool IsValidStackFramePointer(struct StackFrame *x) {
+  /* assumes __mmi_lock() is held */
   return IsLegalPointer(x) && !((uintptr_t)x & 15) &&
          (IsStaticStackFrame((uintptr_t)x >> 16) ||
           IsSigAltStackFrame((uintptr_t)x >> 16) ||