usnic: squash warnings from perf improvements

Should be included in usnic v1.7.3 roll-up CMR (refs trac:3760)

This commit was SVN r29134.

The following Trac tickets were found above:
  Ticket 3760 --> https://svn.open-mpi.org/trac/ompi/ticket/3760

ompi/mca/btl/usnic/btl_usnic_component.c

@@ -970,7 +970,6 @@ static int usnic_component_progress_2(void)
     uint32_t i;
     int j, count = 0, num_events;
     struct ibv_recv_wr *bad_wr;
-    struct ibv_wc* cwc;
     ompi_btl_usnic_module_t* module;
     static struct ibv_wc wc[OMPI_BTL_USNIC_NUM_WC];
     ompi_btl_usnic_channel_t *channel;

ompi/mca/btl/usnic/btl_usnic_recv.h

@@ -247,7 +247,6 @@ ompi_btl_usnic_recv_fast(ompi_btl_usnic_module_t *module,
     mca_btl_active_message_callback_t* reg;
     ompi_btl_usnic_seq_t seq;
     ompi_btl_usnic_endpoint_t *endpoint;
-    uint32_t window_index;
     int i;
 
     bseg = &seg->rs_base;
@@ -300,7 +299,7 @@ drop:
 
 /*
  */
-static inline int
+static inline void
 ompi_btl_usnic_recv_frag_bookeeping(
     ompi_btl_usnic_module_t* module,
     ompi_btl_usnic_recv_segment_t *seg,
@@ -347,8 +346,6 @@ ompi_btl_usnic_recv(ompi_btl_usnic_module_t *module,
     ompi_btl_usnic_segment_t *bseg;
     mca_btl_active_message_callback_t* reg;
     ompi_btl_usnic_endpoint_t *endpoint;
-    ompi_btl_usnic_btl_chunk_header_t *chunk_hdr;
-    uint32_t window_index;
 #if MSGDEBUG1
     char src_mac[32];
     char dest_mac[32];