make: fail when ACI.txt or API.txt differs from values in source code

This regression was caused by commit 6acaf73b0c before this commit make rpms failed when API.txt did not match api

https://fedorahosted.org/freeipa/ticket/5865

Reviewed-By: Lukas Slebodnik <lslebodn@redhat.com>

Makefile

@@ -188,7 +188,7 @@ version-update: release-update
 	fi
 
 	if [ "$(SKIP_API_VERSION_CHECK)" != "yes" ]; then \
-		./makeapi --validate; \
+		./makeapi --validate && \
 		./makeaci --validate; \
 	fi