rgw: Silence warning: control reaches end of non-void function

rgw: Silence warning: control reaches end of non-void function

Build shows:
[ 53%] Building CXX object src/mds/CMakeFiles/mds.dir/JournalPointer.cc.o
ceph/src/rgw/rgw_rest_s3.cc: In member function ‘RGWOp* RGWHandler_REST_Bucket_S3::get_obj_op(bool)’:
ceph/src/rgw/rgw_rest_s3.cc:3588:5: warning: control reaches end of non-void function [-Wreturn-type]
   }   }
     ^
Fixes: 4ffc765c4c5debc665ade7769c4647c3a7278fd2
Fixes: http://tracker.ceph.com/issues/40747
Signed-off-by: Jos Collin <jcollin@redhat.com>
(cherry picked from commit abb2451dd5164e6b610589207b900a6464e21282)