Cleanup include (facebook#8208)

Summary:
Pull Request resolved: facebook#8208

Make include of "file_system.h" use the same include path as everywhere
else.

Reviewed By: riversand963, akankshamahajan15

Differential Revision: D27881606

fbshipit-source-id: fc1e076229fde21041a813c655ce017b5070c8b3

utilities/fault_injection_fs.h

@@ -22,7 +22,7 @@
 #include <string>
 
 #include "file/filename.h"
-#include "include/rocksdb/file_system.h"
+#include "rocksdb/file_system.h"
 #include "util/mutexlock.h"
 #include "util/random.h"
 #include "util/thread_local.h"