INTRO-118 enabling USDT probes in zones should be more scalable

*** 265,274 ****
--- 265,275 ----
          dt_list_t dt_lib_path;  /* linked-list forming library search path */
          uint_t dt_lazyload;     /* boolean:  set via -xlazyload */
          uint_t dt_droptags;     /* boolean:  set via -xdroptags */
          uint_t dt_active;       /* boolean:  set once tracing is active */
          uint_t dt_stopped;      /* boolean:  set once tracing is stopped */
+         uint_t dt_optset;       /* boolean:  set once options have been set */
          processorid_t dt_beganon; /* CPU that executed BEGIN probe (if any) */
          processorid_t dt_endedon; /* CPU that executed END probe (if any) */
          uint_t dt_oflags;       /* dtrace open-time options (see dtrace.h) */
          uint_t dt_cflags;       /* dtrace compile-time options (see dtrace.h) */
          uint_t dt_dflags;       /* dtrace link-time options (see dtrace.h) */