Merge pull request #7632 from erikh/fix_check_config

fix check-config.sh to check for CGROUP_PERF

contrib/check-config.sh

@@ -146,6 +146,7 @@ echo 'Optional Features:'
 flags=(
 	MEMCG_SWAP
 	RESOURCE_COUNTERS
+	CGROUP_PERF
 )
 check_flags "${flags[@]}"