Fix bug whereby a webserver closing stdout from the CGI/FastCGI binary

would cause PHP to get caught in an infinite loop of failing write()
syscalls.

sapi/cgi/cgi_main.c

@@ -254,6 +254,7 @@ static int sapi_cgibin_ub_write(const char *str, uint str_length TSRMLS_DC)
 		ret = sapi_cgibin_single_write(ptr, remaining TSRMLS_CC);
 		if (!ret) {
 			php_handle_aborted_connection();
+			return str_length - remaining;
 		}
 		ptr += ret;
 		remaining -= ret;