3006 VERIFY[S,U,P] and ASSERT[S,U,P] frequently check if first argument is zero

*** 18,29 ****
--- 18,31 ----
   *
   * CDDL HEADER END
   */
  /*
   * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
+  * Copyright (c) 2012 by Delphix. All rights reserved.
   */
  
+ 
  #include <sys/zfs_context.h>
  
  list_t zfs_dbgmsgs;
  int zfs_dbgmsg_size;
  kmutex_t zfs_dbgmsgs_lock;
*** 46,56 ****
                  int size = sizeof (zfs_dbgmsg_t) + strlen(zdm->zdm_msg);
                  kmem_free(zdm, size);
                  zfs_dbgmsg_size -= size;
          }
          mutex_destroy(&zfs_dbgmsgs_lock);
!         ASSERT3U(zfs_dbgmsg_size, ==, 0);
  }
  
  /*
   * Print these messages by running:
   *      echo ::zfs_dbgmsg | mdb -k
--- 48,58 ----
                  int size = sizeof (zfs_dbgmsg_t) + strlen(zdm->zdm_msg);
                  kmem_free(zdm, size);
                  zfs_dbgmsg_size -= size;
          }
          mutex_destroy(&zfs_dbgmsgs_lock);
!         ASSERT0(zfs_dbgmsg_size);
  }
  
  /*
   * Print these messages by running:
   * echo ::zfs_dbgmsg | mdb -k