Import C++ Standard Template Library

You can now use the hardest fastest and most dangerous language there is
with Cosmopolitan. So far about 75% of LLVM libcxx has been added. A few
breaking changes needed to be made to help this go smoothly.

- Rename nothrow to dontthrow
- Rename nodiscard to dontdiscard
- Add some libm functions, e.g. lgamma, nan, etc.
- Change intmax_t from int128 to int64 like everything else
- Introduce %jjd formatting directive for int128_t
- Introduce strtoi128(), strtou128(), etc.
- Rename bsrmax() to bsr128()

Some of the templates that should be working currently are std::vector,
std::string, std::map, std::set, std::deque, etc.

third_party/chibicc/test/common.c

@@ -17,8 +17,8 @@ void Assert2(long expected, long actual, char *code, char *func, int line) {
 
 void Assert128(__int128 k, __int128 x, char *code, char *func, int line) {
   if (k != x) {
-    fprintf(stderr, "%s:%d: %s => want %jd but got %jd\n", func, line, code, k,
-            x);
+    fprintf(stderr, "%s:%d: %s => want %jjd but got %jjd\n", func, line, code,
+            k, x);
     exit(1);
   }
 }