Fix for a common race condition when running the Sandia mt_send_recv.cc test.

A segfault would occur in mca_pml_ob1_recv_request_progress() when trying to prepare the convertor for unpacking, because the request's req_proc field was NULL.

Turns out that we weren't setting the req_proc field in the MCA_PML_OB1_CHECK_SPECIFIC_AND_WILD_RECEIVES_FOR_MATCH macro.  Instead of just setting it there I removed the other place req_proc was being set correctly, and instead took care of all the cases at once in mca_pml_ob1_recv_frag_match().

This commit was SVN r12323.

ompi/mca/pml/ob1/pml_ob1_recvfrag.c

@@ -228,7 +228,6 @@ void mca_pml_ob1_recv_frag_callback(
         if( generic_recv != (mca_pml_ob1_recv_request_t *)                         \
             opal_list_get_end(generic_receives) ) {                                \
                                                                                    \
-            generic_recv->req_recv.req_base.req_proc = proc->ompi_proc;            \
             /* Match made */                                                       \
             return_match = generic_recv;                                           \
                                                                                    \
@@ -551,6 +550,7 @@ rematch:
 
         /* if match found, process data */
         if (match) {
+            match->req_recv.req_base.req_proc = proc->ompi_proc;
 
             /*
              * update delivered sequence number information, if needed.