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

@@ -265,10 +265,11 @@
         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) */