Bug 1630376 - Add errno.h header to RNP clang-cl compatibility code. DONTBUILD r=kaie

Differential Revision: https://phabricator.services.mozilla.com/D71092

--HG--
extra : moz-landing-system : lando

third_party/niwcompat/sys/time.h

@@ -11,6 +11,7 @@ extern "C" {
 #endif
 
 /* MS Win SDK Headers */
+#include <errno.h>
 #include <sys/timeb.h> /* For _ftime_s */
 #include <time.h>