smf: switch to a tri-state for process-security properties true=on,false=off,nil=default

*** 56,72 ****
                    The stack will be mapped without executable permission, and
                    attempts to execute it will fault.
  
         System default security-flags are configured via properties on the
         svc:/system/process-security service, which contains a boolean property
!        per-flag in the default, lower and upper, property groups.  For
!        example, to enable ASLR by default you would execute the following
!        commands:
  
           # svccfg -s svc:/system/process-security setprop default/aslr = true
  
  
         This can be done by any user with the solaris.smf.value.process-
         security authorization.
  
         Since security-flags are strictly inherited, this will not take effect
         until the system or zone is next booted.
--- 56,78 ----
                    The stack will be mapped without executable permission, and
                    attempts to execute it will fault.
  
         System default security-flags are configured via properties on the
         svc:/system/process-security service, which contains a boolean property
!        per-flag in the default, lower and upper, property groups.  The value
!        indicates the setting of the flag, flags with no value take their
!        defaults.  For example, to enable ASLR by default you would execute the
!        following commands:
  
           # svccfg -s svc:/system/process-security setprop default/aslr = true
  
  
+        To restore the setting to the defaults you would execute:
+ 
+          # svccfg -s svc:/system/process-security delpropvalue default/aslr true
+ 
+ 
         This can be done by any user with the solaris.smf.value.process-
         security authorization.
  
         Since security-flags are strictly inherited, this will not take effect
         until the system or zone is next booted.