afs: put back conn if not using in checkserver loop

we get a conn, check it for eligibility, and if not,
just abandon it. "oops"

(cherry picked from commit 26fc0cda94c24a1c5f0bef109bca920456c25265)

Change-Id: I8e4f762b5170f07d6abc3508e88f001ca147c3a7
Reviewed-on: http://gerrit.openafs.org/6521
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>

src/afs/afs_server.c

@@ -640,7 +640,8 @@ afs_CheckServers(int adown, struct cell *acellp)
 		conntimer[nconns]=0;
 	    }
 	    nconns++;
-	}
+	} else /* not holding, kill ref */
+	    afs_PutConn(tc, rxconn, SHARED_LOCK);
     } /* Outer loop over addrs */
 
     AFS_GUNLOCK();