Revert "version up: MariaRocks 10.2.12"

This reverts commit 6cb00ff0,
because of a regression in InnoDB (https://jira.mariadb.org/browse/MDEV-14614).
Several functional tests started to fail with 10.2.12.

component/mariadb/mariarocks.cfg

 # Do not extend any file that touch buildout:parts.
 
 [mariadb]
-version = 10.2.12
-md5sum = c5bce588e3c53ebc417e37ecb0967aee
+version = 10.2.11
+md5sum = 954088299fe5f11b4fda3b540558adbd
 stable-patches =
 configure-options +=
+# force build of TokuDB due to a regression in 10.2.11
+  -DTOKUDB_OK=1
   -DCMAKE_C_COMPILER=${gcc:location}/bin/gcc
   -DCMAKE_CXX_COMPILER=${gcc:location}/bin/g++
 extra_cflags = -I${zstd:location}/include