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.

.vscode/c_cpp_properties.json

@@ -15,7 +15,7 @@
 				"alignas(x)",
 				"alignof(x)",
 				"artificial=",
-				"nodiscard=",
+				"dontdiscard=",
 				"mayalias=",
 				"forceinline=",
 				"forcealign(x)=",
@@ -48,7 +48,7 @@
 				"nosideeffect=",
 				"unreachable=",
 				"thatispacked=",
-				"nothrow=",
+				"dontthrow=",
 				"nocallback=",
 				"relegated=",
 				"hidden=",