Add chibicc

This program popped up on Hacker News recently. It's the only modern
compiler I've ever seen that doesn't have dependencies and is easily
modified. So I added all of the missing GNU extensions I like to use
which means it might be possible soon to build on non-Linux and have
third party not vendor gcc binaries.

libc/calls/fstat-nt.c

@@ -34,8 +34,8 @@
 textwindows int fstat$nt(int64_t handle, struct stat *st) {
   int filetype;
   uint64_t actualsize;
-  struct NtByHandleFileInformation wst;
   struct NtFileCompressionInfo fci;
+  struct NtByHandleFileInformation wst;
   if (GetFileInformationByHandle(handle, &wst)) {
     memset(st, 0, sizeof(*st));
     filetype = GetFileType(handle);