uts: add a concept of a 'default' set of privileges, separate from 'basic'

*** 91,100 ****
--- 91,104 ----
  $endif
  $if _x86 && _ELF64
  $add amd64
  $endif
  
+ SYMBOL_VERSION ILLUMOS_0.20 {   # priv_defaultset
+         priv_defaultset;
+ } ILLUMOS_0.19;
+ 
  SYMBOL_VERSION ILLUMOS_0.19 {   # flock
      protected:
          flock;
  } ILLUMOS_0.18;