Issue with updmap-sys use of symlinks in cross platform installation

[Karl Berry]

    Would a solution be to add a configuration variable for updmap that
    could be used to force the use of copy instead of symlinks?

It would be easy enough to do that, but I prefer simply to
unconditionally do a copy and never use symlinks. Doesn't that solve all
the problem cases with no practical downside? 

Reinhard, in principle I agree with you but in this particular case I
don't see an advantage to symlinks that outweighs the simplification in
code and configuration and documentation.

We can keep the symlink code in place for a while, just in case. So the
change amounts to adding $opts{"copy"} = 1 (or equivalent) to make the
default be copy.

I just made did this (plus tweaked the help msg, etc.), in r70707.
Hope it flies. --thanks, karl.