fix a header include

Summary:
need to consistently include "rocksdb/persistent_cache.h" to fix internal build
Closes https://github.com/facebook/rocksdb/pull/2034

Differential Revision: D4768101

Pulled By: ajkr

fbshipit-source-id: 2ecb07f

table/persistent_cache_options.h

@@ -6,7 +6,7 @@
 
 #include <string>
 
-#include "include/rocksdb/persistent_cache.h"
+#include "rocksdb/persistent_cache.h"
 #include "util/statistics.h"
 
 namespace rocksdb {