5083 avoid undefined order of operations in assignments

*** 22,33 ****
  /*
   * Copyright 2002 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   */
  
- #pragma ident   "%Z%%M% %I%     %E% SMI"
- 
  /*
   * smq.c: to provide a message queue system for scadm functions (used in the
   * firmware download context where BP messages, received from the service
   * processor, are stored in the message queue)
   *
--- 22,31 ----
*** 89,100 ****
                  return (SMQ_ERROR);
  
          /* Copy messaged into queue */
          *msg = *smq->smq_head;
  
!         /* Increment Head */
!         smq->smq_head = smq->smq_head++;
          if ((unsigned long)smq->smq_head > ((unsigned long)smq->smq_msgBuffer +
              (unsigned long)(smq->smq_depth * sizeof (smq_msg_t)))) {
                  smq->smq_head = smq->smq_msgBuffer;
          }
          smq->smq_count--;
--- 87,97 ----
                  return (SMQ_ERROR);
  
          /* Copy messaged into queue */
          *msg = *smq->smq_head;
  
!         smq->smq_head++;
          if ((unsigned long)smq->smq_head > ((unsigned long)smq->smq_msgBuffer +
              (unsigned long)(smq->smq_depth * sizeof (smq_msg_t)))) {
                  smq->smq_head = smq->smq_msgBuffer;
          }
          smq->smq_count--;
*** 113,124 ****
                  return (SMQ_FULL);
  
          /* Copy messaged into queue */
          *smq->smq_tail = *msg;
  
!         /* Increment Tail */
!         smq->smq_tail = smq->smq_tail++;
          if ((unsigned long)smq->smq_tail > ((unsigned long)smq->smq_msgBuffer +
              (unsigned long)(smq->smq_depth * sizeof (smq_msg_t)))) {
                  smq->smq_tail = smq->smq_msgBuffer;
          }
  
--- 110,120 ----
                  return (SMQ_FULL);
  
          /* Copy messaged into queue */
          *smq->smq_tail = *msg;
  
!         smq->smq_tail++;
          if ((unsigned long)smq->smq_tail > ((unsigned long)smq->smq_msgBuffer +
              (unsigned long)(smq->smq_depth * sizeof (smq_msg_t)))) {
                  smq->smq_tail = smq->smq_msgBuffer;
          }
  
*** 173,184 ****
                  return (SMQ_ERROR);
  
          /* Copy messaged into queue */
          *msg = *smq->smq_head;
  
!         /* Increment Head */
!         smq->smq_head = smq->smq_head++;
          if ((unsigned long)smq->smq_head > ((unsigned long)smq->smq_msgBuffer +
              (unsigned long)(smq->smq_depth * sizeof (smq_msg_t)))) {
                  smq->smq_head = smq->smq_msgBuffer;
          }
          smq->smq_count--;
--- 169,179 ----
                  return (SMQ_ERROR);
  
          /* Copy messaged into queue */
          *msg = *smq->smq_head;
  
!         smq->smq_head++;
          if ((unsigned long)smq->smq_head > ((unsigned long)smq->smq_msgBuffer +
              (unsigned long)(smq->smq_depth * sizeof (smq_msg_t)))) {
                  smq->smq_head = smq->smq_msgBuffer;
          }
          smq->smq_count--;