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.

third_party/python/pycomp.c

@@ -77,7 +77,6 @@ void
 GetOpts(int argc, char *argv[])
 {
     int opt;
-    char *outdir;
     while ((opt = getopt(argc, argv, "hnO:o:")) != -1) {
         switch (opt) {
         case 'O':
@@ -114,7 +113,7 @@ main(int argc, char *argv[])
     ssize_t rc;
     size_t i, n;
     struct stat st;
-    char *s, *p, m[12];
+    char *p, m[12];
     PyObject *code, *marshalled;
     ShowCrashReports();
     GetOpts(argc, argv);