rocksdb: pull up to latest master

This includes our replay fixes, which are now upstream.

Signed-off-by: Sage Weil <sage@redhat.com>

diff --git a/src/rocksdb b/src/rocksdb
index fa98456ccbd860120127ac2e91a2088fb222606e..936973d1452b773cd110e2d8605572d7a883e644 160000 (submodule)
--- a/src/rocksdb
+++ b/src/rocksdb
@@ -1 +1 @@
-Subproject commit fa98456ccbd860120127ac2e91a2088fb222606e
+Subproject commit 936973d1452b773cd110e2d8605572d7a883e644