rgw: revert unintentional change to civetweb

https://github.com/ceph/ceph/pull/11800 uninternionally updated
the civetweb submodule.

Signed-off-by: Bassam Tabbara <bassam.tabbara@quantum.com>

diff --git a/src/civetweb b/src/civetweb
index e12494070432b85d5ffce7dece81c0baad457a5f..cc0dfa11dadfca8a7021687aa537a3d377f244cb 160000 (submodule)
--- a/src/civetweb
+++ b/src/civetweb
@@ -1 +1 @@
-Subproject commit e12494070432b85d5ffce7dece81c0baad457a5f
+Subproject commit cc0dfa11dadfca8a7021687aa537a3d377f244cb