strace: Fix "over-optimization" flaw in strace.

Recent versions of gcc are optimizing away the TLS buffer allocated in
main, so we need to tell gcc that it's really used.  RtlSecureZeroMemory
accomplishes this while also inlining the memset.

Signed-off-by: Daniel Santos <daniel.santos@pobox.com>

winsup/utils/strace.cc

@@ -1191,7 +1191,7 @@ main (int argc, char **argv)
      registry setting to 0x100000 (TOP_DOWN). */
   char buf[CYGTLS_PADSIZE];
 
-  memset (buf, 0, sizeof (buf));
+  RtlSecureZeroMemory (buf, sizeof (buf));
   exit (main2 (argc, argv));
 }