Clean up more code

- Found some bugs in LLVM compiler-rt library
- The useless LIBC_STUBS package is now deleted
- Improve the overflow checking story even further
- Get chibicc tests working in MODE=dbg mode again
- The libc/isystem/ headers now have correctly named guards

third_party/libcxx/__bsd_locale_fallbacks.h

@@ -14,7 +14,6 @@
 #define _LIBCPP_BSD_LOCALE_FALLBACKS_DEFAULTS_H
 
 #include "third_party/libcxx/stdlib.h"
-#include "libc/mem/fmt.h"
 #include "libc/str/unicode.h"
 #include "libc/fmt/fmt.h"
 #include "libc/str/locale.h"

third_party/libcxx/ctime

@@ -12,6 +12,7 @@
 
 #include "third_party/libcxx/__config"
 #include "libc/calls/weirdtypes.h"
+#include "libc/calls/calls.h"
 #include "libc/isystem/time.h"
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)

third_party/libcxx/libcxx.mk

@@ -189,7 +189,6 @@ THIRD_PARTY_LIBCXX_A_DIRECTDEPS =				\
 	LIBC_RUNTIME						\
 	LIBC_STDIO						\
 	LIBC_STR						\
-	LIBC_STUBS						\
 	LIBC_SYSV						\
 	LIBC_TIME						\
 	LIBC_THREAD						\