tree-wide: apply equals-null.cocci

Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/clone.c

@@ -1070,10 +1070,10 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 	 * apply the remote name provided by --origin only after this second
 	 * call to git_config, to ensure it overrides all config-based values.
 	 */
-	if (option_origin != NULL)
+	if (option_origin)
 		remote_name = xstrdup(option_origin);
 
-	if (remote_name == NULL)
+	if (!remote_name)
 		remote_name = xstrdup("origin");
 
 	if (!valid_remote_name(remote_name))