op.c: Don't fold constant fc() in locale

op.c: Don't fold constant fc() in locale

We do compile time folding of calls to ops with constant parameters.
This should be skipped if the op's result depends on locale, and it is
being called from within the scope of 'use locale', as the result is not
known until runtime.  fc() was folding anyway.

There is no test, as this only shows up when run in a locale that it
makes a difference in, and there is no guarantee that such a locale
would occur on any computer, and it is a real pain to go searching
through the computer's available locales for such a one for just this
error.