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.

tool/decode/mkcombos.c

@@ -105,7 +105,7 @@ int main(int argc, char *argv[]) {
     strsep(&tok, ";");
     category = strsep(&tok, ";");
     if (!s1 || !category) continue;
-    bit = strtoimax(s1, NULL, 16);
+    bit = strtol(s1, NULL, 16);
     if (bit != 0x00AD &&
         ((0x1160 <= bit && bit <= 0x11FF) ||
          (strcmp(category, "Me") == 0 || strcmp(category, "Mn") == 0 ||