Fix warnings

This change fixes Cosmopolitan so it has fewer opinions about compiler
warnings. The whole repository had to be cleaned up to be buildable in
-Werror -Wall mode. This lets us benefit from things like strict const
checking. Some actual bugs might have been caught too.

tool/build/chmod.c

@@ -58,7 +58,7 @@ static void GetOpts(int argc, char *argv[]) {
 
 int main(int argc, char *argv[]) {
   int i, mode;
-  char buf[PATH_MAX], *endptr;
+  char *endptr;
   prog = argv[0];
   if (!prog) prog = "chmod";
   GetOpts(argc, argv);