fixup! mariadb: explicitly extends 'gcc' for RocksDB

component/mariadb/buildout.cfg

@@ -17,6 +17,9 @@ extends =
   ../readline/buildout.cfg
   ../xz-utils/buildout.cfg
   ../zlib/buildout.cfg
+# The following lines are only for mariarocks.cfg
+# to be extended last without touching 'parts'.
+  ../gcc/buildout.cfg
 
 parts =
   mariadb

component/mariadb/mariarocks.cfg

-[buildout]
-extends =
-  ../gcc/buildout.cfg
+# Do not extend any file that touch buildout:parts.
 
 [mariadb]
 url = https://downloads.mariadb.com/MariaDB/mariadb-10.2.6/source/mariadb-10.2.6.tar.gz