Add a check that Raft is configured into the set-get-cas functions.

Author: kvap

multimaster.c

@@ -2375,6 +2375,9 @@ void* RaftableGet(char const* key, int* size, RaftableTimestamp* ts, bool nowait
 {
 	size_t s;
 	char *value;
+
+	if (!MtmUseRaftable) return NULL;
+
 	Assert(ts == NULL); /* not implemented */
 	value = raftable_get(key, &s);
 	*size = s;
@@ -2383,11 +2386,15 @@ void* RaftableGet(char const* key, int* size, RaftableTimestamp* ts, bool nowait
 
 void  RaftableSet(char const* key, void const* value, int size, bool nowait)
 {
+	if (!MtmUseRaftable) return;
+
 	raftable_set(key, value, size, nowait ? 0 : -1);
 }
 
 bool  RaftableCAS(char const* key, char const* value, bool nowait)
 {
+	if (!MtmUseRaftable) return false;
+
 	Assert(false); /* not implemented */
 	return false;
 }