Clear method caches when unwinding local *foo=*method
It was already working for those cases where *foo contained a sub
before and after localisation. For those cases where *foo had no sub
but localised assignment gave it one, method caches were not being
reset on scope exit.
case SAVEt_GP in scope.c:leave_scope needs to look at both GPs (glob
pointer, or list of glob slots), both from before and after the unlo-
calisation. If either has a sub, method caches need to be cleared.
This does not yet fix local *foo = sub {}, but I added a to-do
test for it. (This is more complicated, as localisation happens in
two seperate steps, the glob slot localisation storing no pointers to
the glob itself on the savestack.)