osd/RadosModel.h: init non-static member in ctor

Fix for:

CID 1188182 (#1 of 1): Uninitialized pointer field (UNINIT_CTOR)
 uninit_member: Non-static class member rcompletion is not initialized
  in this constructor nor in any functions that it calls.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>

Author: dalgaaf

src/test/osd/RadosModel.h

@@ -727,7 +727,8 @@ class WriteOp : public TestOp {
 	  bool do_excl,
 	  TestOpStat *stat = 0)
     : TestOp(n, context, stat),
-      oid(oid), waiting_on(0), last_acked_tid(0), do_append(do_append),
+      oid(oid), rcompletion(NULL), waiting_on(0), 
+      last_acked_tid(0), do_append(do_append),
       do_excl(do_excl)
   {}