fix scope cleanup when next jumps to a continue block; this is rather

fix scope cleanup when next jumps to a continue block; this is rather
in the nature of a kludge; it doesn't fix the longstanding bug that
makes C<while (!$x++) { local $x = 7 } continue { print $x }> print "7"
instead of "1")

p4raw-id: //depot/perl@4848