component/mariadb: improve ad-hoc patch to build RocksDB on old glibc.

component/mariadb/mariarocks.cfg

@@ -3,7 +3,7 @@ url = https://downloads.mariadb.com/MariaDB/mariadb-10.2.5/source/mariadb-10.2.5
 md5sum = 16fb01bb375c8d8a91a9ecf491397d51
 pre-configure =
   sed -i -e '/(rc == -1 || errno == EINTR)/s/||/\&\&/' libmariadb/plugins/pvio/pvio_socket.c
-  sed -i -e 's, rocksdblib, rocksdblib "rt",' storage/rocksdb/CMakeLists.txt
+  sed -i -e 's,set(SYSTEM_LIBS $${CMAKE_THREAD_LIBS_INIT}),set(SYSTEM_LIBS $${CMAKE_THREAD_LIBS_INIT} $${LIBRT}),' storage/rocksdb/build_rocksdb.cmake
 configure-options +=
   -DPLUGIN_DAEMON_EXAMPLE=NO
   -DPLUGIN_EXAMPLE=NO