7029 want per-process exploit mitigation features (secflags)
7030 want basic address space layout randomization (aslr)
7031 noexec_user_stack should be a secflag
7032 want a means to forbid mappings around NULL.

@@ -319,10 +319,12 @@
         p0.p_as = &kas;
         p0.p_lockp = &p0lock;
         p0.p_brkpageszc = 0;
         p0.p_t1_lgrpid = LGRP_NONE;
         p0.p_tr_lgrpid = LGRP_NONE;
+        psecflags_default(&p0.p_secflags);
+
         sigorset(&p0.p_ignore, &ignoredefault);
 
         CPU->cpu_thread = &t0;
         bzero(&cpu0_disp, sizeof (disp_t));
         CPU->cpu_disp = &cpu0_disp;