[tex-live] small bug re installing x86_64-darwin vs. universal-darwin

[Jack]

I think there is a small bug in texlive when installing on a 64-bit
Mac running Snow Leopard or greater.  Specifically, I found it
impossible to install to either a Lion or Mountain Lion Mac in such a
way that the resulting binaries are x64_64-darwin.

Some searching revealed that the culprit is in TLUtils.pm, lines
288-295, where it says that nothing but universal-darwin will get
installed because we don't want to accidentally clobber a Leopard
install.

I worked around this by changing line 294 directly to replace "i386"
with "x86_64", and that worked.  But a user shouldn't have to do this.

Surely there is a way for one of these installation scripts to test
whether a machine recognized as 64-bit capable is running Leopard or
not, right?  I think care *should* be taken not to ruin installation
on a Leopard machine; I just think this can be done while allowing
Snow & Greater their fun too.  Not knowing any perl, I can't offer a
patch however.

Probably nobody noticed this because Mac users tend to use MacTeX.  I
install from the install-tl script.

Cheers,
--Jack