7127  remove -Wno-missing-braces from Makefile.uts

*** 70,80 ****
  
  static taskq_t *xbuf_tq = NULL;
  static int xbuf_attr_tq_minalloc = XBUF_TQ_MINALLOC;
  static int xbuf_attr_tq_maxalloc = XBUF_TQ_MAXALLOC;
  
! static kmutex_t xbuf_mutex = { 0 };
  static uint32_t xbuf_refcount = 0;
  
  /*
   * Private wrapper for buf cloned via ddi_xbuf_qstrategy()
   */
--- 70,80 ----
  
  static taskq_t *xbuf_tq = NULL;
  static int xbuf_attr_tq_minalloc = XBUF_TQ_MINALLOC;
  static int xbuf_attr_tq_maxalloc = XBUF_TQ_MAXALLOC;
  
! static kmutex_t xbuf_mutex = { {NULL} };
  static uint32_t xbuf_refcount = 0;
  
  /*
   * Private wrapper for buf cloned via ddi_xbuf_qstrategy()
   */