Fix [-Wstrict-prototypes] warnings in MySQLi extension

errno is a global variable/macro which is implementation defined and should not be reused

Author: Girgias

ext/mysqli/mysqli_warning.c

@@ -129,7 +129,7 @@ MYSQLI_WARNING * php_get_warnings(MYSQLND_CONN_DATA * mysql)
 
 	for (;;) {
 		zval *entry;
-		int errno;
+		int php_mysqli_errno;
 
 		mysqlnd_fetch_into(result, MYSQLND_FETCH_NUM, &row, MYSQLND_MYSQLI);
 		if (Z_TYPE(row) != IS_ARRAY) {
@@ -142,13 +142,13 @@ MYSQLI_WARNING * php_get_warnings(MYSQLND_CONN_DATA * mysql)
 
 		/* 1. Here comes the error no */
 		entry = zend_hash_get_current_data(Z_ARRVAL(row));
-		errno = zval_get_long(entry);
+		php_mysqli_errno = zval_get_long(entry);
 		zend_hash_move_forward(Z_ARRVAL(row));
 
 		/* 2. Here comes the reason */
 		entry = zend_hash_get_current_data(Z_ARRVAL(row));
 
-		w = php_new_warning(entry, errno);
+		w = php_new_warning(entry, php_mysqli_errno);
 		/*
 		  Don't destroy entry, because the row destroy will decrease
 		  the refcounter. Decreased twice then mysqlnd_free_result()