Method cache invalidation should be a namespace function

[kjs]

In src/global.c:Parrot_store_global_s() there is the todo item:

/* FIXME - method cache invalidation should be a namespace function */ Parrot_invalidate_method_cache(interp, str_key, globalname);

Previously tracked in RT#46169.

See also ticket RT#39430 (RT#46169 is dependent on that).

[whiteknight]

This is basically a duplicate of #1224, which was just closed as invalid. This, the same.