Revert "Implement $*USER and $*GROUP (not yet specced)"

There is something wrong with my understanding of how either Proxy.new works,
or matching, or whatever, but if your user name / group contains non \w
characters, you will get 4 warnings everytime you start up.  And I don't have
time to look at why exactly now.

src/core/Process.pm

@@ -22,42 +22,6 @@
     PROCESS::<$PROGRAM_NAME> = $PROGRAM_NAME;
 
     PROCESS::<$TMPDIR> = IO::Spec.tmpdir().path;
-
-    class IdName {
-        has Int $.id;
-        has Str $.name;
-
-        method Numeric { $!id }
-        method Str     { $!name }
-        method gist    { "$!name ($!id)" }
-    }
-
-    # probably needs some nqp::op, LHF for someone?
-    my $on_demand_fetch = Proxy.new(
-      FETCH => {
-          if try qx/id/ -> $id {
-              $id ~~ m/^
-                [ uid "=" $<uid>=(\d+) ]
-                [ "(" $<user>=(\w+) ")" ]
-                \s+
-                [ gid "=" $<gid>=(\d+) ]
-                [ "(" $<group>=(\w+) ")" ]
-              /;
-
-              PROCESS::<$USER>  := IdName.new( :id(+$<uid>), :name(~$<user>) );
-              PROCESS::<$GROUP> := IdName.new( :id(+$<gid>), :name(~$<group>) );
-          }
-
-          # alas, no support yet
-          else {
-              PROCESS::<$USER>     := Nil;
-              PROCESS::<$GROUP>    := Nil;
-          }
-      }
-    );
-
-    PROCESS::<$USER>     //= $on_demand_fetch;
-    PROCESS::<$GROUP>    //= $on_demand_fetch;
 }
 
 # vim: ft=perl6 expandtab sw=4