Fixed bug #62889

Our minimum libmysqlclient version requirement is high enough
that we don't need to check for MYSQL_OPT_LOCAL_INFILE support.

However, the mysql_get_option() function seems to only be available
since 5.7 (though it's really hard to find any definitie information
on when MySQL introduced certain functions or changes...) so we
need to store the value of the flag locally to make it available
through getAttribute().

ext/pdo_mysql/php_pdo_mysql_int.h

@@ -104,6 +104,7 @@ typedef struct {
 	unsigned buffered:1;
 	unsigned emulate_prepare:1;
 	unsigned fetch_table_names:1;
+	unsigned local_infile:1;
 #ifndef PDO_USE_MYSQLND
 	zend_ulong max_buffer_size;
 #endif