Merge pull request laradock#760 from bestlong/patch-1

fix php-fpm PHP56 can't enabled MySQL Support

Author: Mahmoudz

docker-compose.yml

@@ -64,6 +64,7 @@ services:
           - INSTALL_EXIF=${PHP_FPM_INSTALL_EXIF}
           - INSTALL_AEROSPIKE_EXTENSION=${PHP_FPM_INSTALL_AEROSPIKE_EXTENSION}
           - INSTALL_MYSQLI=${PHP_FPM_INSTALL_MYSQLI}
+          - INSTALL_MYSQL=${PHP_FPM_INSTALL_MYSQL}
           - INSTALL_TOKENIZER=${PHP_FPM_INSTALL_TOKENIZER}
           - INSTALL_INTL=${PHP_FPM_INSTALL_INTL}
         dockerfile: "Dockerfile-${PHP_VERSION}"