Fix compiler warnings - unused variables

Warnings related to unused variables intended to be used for debugging, but
always declared.
Signed-off-by: Wesley Bland <wbland@mcs.anl.gov>

src/mpid/ch3/channels/nemesis/netmod/tcp/socksm.c

@@ -1903,7 +1903,9 @@ int MPID_nem_tcp_state_listening_handler(struct pollfd *const unused_1, sockconn
         len = sizeof(SA_IN);
         MPIU_DBG_MSG_FMT(NEM_SOCK_DET, VERBOSE, (MPIU_DBG_FDEST, "before accept"));
         if ((connfd = accept(l_sc->fd, (SA *) &rmt_addr, &len)) < 0) {
+#ifdef HAVE_ERROR_CHECKING
             int save_errno = errno;
+#endif
             MPIU_DBG_MSG_FMT(NEM_SOCK_DET, VERBOSE, (MPIU_DBG_FDEST, "after accept, l_sc=%p lstnfd=%d connfd=%d, errno=%d:%s ", l_sc, l_sc->fd, connfd, errno, MPIU_Strerror(save_errno)));
             if (errno == EINTR) 
                 continue;

src/mpid/ch3/src/mpid_imrecv.c

@@ -115,7 +115,9 @@ int MPID_Imrecv(void *buf, int count, MPI_Datatype datatype,
     else
     {
         /* --BEGIN ERROR HANDLING-- */
+#ifdef HAVE_ERROR_CHECKING
         int msg_type = MPIDI_Request_get_msg_type(rreq);
+#endif
         MPID_Request_release(rreq);
         rreq = NULL;
         MPIU_ERR_SETANDJUMP1(mpi_errno,MPI_ERR_INTERN, "**ch3|badmsgtype",

src/mpid/ch3/src/mpid_irecv.c

@@ -124,7 +124,9 @@ int MPID_Irecv(void * buf, int count, MPI_Datatype datatype, int rank, int tag,
 	else
 	{
 	    /* --BEGIN ERROR HANDLING-- */
+#ifdef HAVE_ERROR_CHECKING
             int msg_type = MPIDI_Request_get_msg_type(rreq);
+#endif
             MPID_Request_release(rreq);
 	    rreq = NULL;
 	    MPIU_ERR_SETANDJUMP1(mpi_errno,MPI_ERR_INTERN, "**ch3|badmsgtype",

src/mpid/ch3/src/mpid_recv.c

@@ -139,7 +139,9 @@ int MPID_Recv(void * buf, int count, MPI_Datatype datatype, int rank, int tag,
 	else
 	{
 	    /* --BEGIN ERROR HANDLING-- */
+#ifdef HAVE_ERROR_CHECKING
             int msg_type = MPIDI_Request_get_msg_type(rreq);
+#endif
             MPID_Request_release(rreq);
 	    rreq = NULL;
 	    MPIU_ERR_SETANDJUMP1(mpi_errno,MPI_ERR_INTERN, "**ch3|badmsgtype",