Don't use separate method for recursing

- basically reverts ed65d73
- apparently, objects in a Match structure *can* be visited multiple
  times, and when they do, create a different result in the structure.

Since the SUBMATCH method did *not* check for visitedness, this resulted
in a different value being returned, which upset a lot of modules in the
ecosystem.  Not sure I want to rework the Match object to make it lazy
anymore.  :-(

src/core.c/Match.pm6

@@ -40,29 +40,6 @@ my class Match is Capture is Cool does NQPMatchRole {
         self
     }
 
-    # Version of MATCH that does *not* need to check for being set up already
-    # as this will only be called from within MATCH-CAPTURES, which by
-    # definition is called only when the Match object is not set up yet.
-    method SUBMATCH() is implementation-detail {
-        nqp::if(                           # must still set up
-          nqp::islt_i(
-            nqp::getattr_i(self,Match,'$!pos'),
-            nqp::getattr_i(self,Match,'$!from')
-          ) || nqp::isnull(my $rxsub := nqp::getattr(self,Match,'$!regexsub'))
-            || nqp::isnull(my $CAPS := nqp::tryfindmethod($rxsub,'CAPS'))
-            || nqp::isnull(my $captures := $CAPS($rxsub))
-            || nqp::not_i($captures.has-captures),
-          nqp::stmts(                      # no captures
-            nqp::bindattr(self,Capture,'@!list',$EMPTY_LIST),
-            nqp::bindattr(self,Capture,'%!hash',$EMPTY_HASH),
-            nqp::bindattr(self,Match,'$!match',NQPdidMATCH)  # mark as set up
-          ),
-          self!MATCH-CAPTURES($captures)  # go reify all the captures
-        );
-
-        self
-    }
-
     method !MATCH-CAPTURES(Mu $captures --> Nil) {
         # Initialize capture lists.
         my $list := nqp::findmethod($captures,'prepare-raku-list')($captures);
@@ -88,7 +65,7 @@ my class Match is Capture is Cool does NQPMatchRole {
                     (my $cursor := nqp::atpos($cs,$i)),
                     nqp::unless(
                       nqp::isnull_s(nqp::getattr_s($cursor,$?CLASS,'$!name')),
-                      nqp::push($dest,$cursor.SUBMATCH)  # recurse
+                      nqp::push($dest,$cursor.MATCH)  # recurse
                     )
                   )
                 );
@@ -106,7 +83,7 @@ my class Match is Capture is Cool does NQPMatchRole {
                       nqp::not_i(nqp::isnull_s($name))
                         && nqp::isge_i(nqp::chars($name),1),
                       nqp::stmts(                           # has a name
-                        (my $match := $cursor.SUBMATCH),  # recurse
+                        (my $match := $cursor.MATCH),  # recurse
                         nqp::if(
                           nqp::iseq_s($name,'$!from')
                             || nqp::iseq_s($name,'$!to'),