[tex-live] use of x86_64-darwin only in mactex 2010

[Richard Koch]

I make the Mac binaries.

The 32 bit binaries work fine on 64 bit machines. Consequently, we have the luxury of
compiling 64 bit binaries on the very latest operating system. Thus x86_64-darwin is
compiled on Snow Leopard and does not work on 64 bit Leopard machines.

It isn't possible to add these binaries to universal-darwin because if we did, 64 bit
machines running Leopard would try to run them and crash.

When these binaries were created, Karl asked me whether they should be the default
binaries on 64-bit Snow Leopard machines. I said "no," and I hope we stick with
that decision. Tests show that the speed increase with 64 bit binaries is very minor.

Last year we supplied 64 bit binaries "on the side, unofficially." I wanted them in TeX
Live this year so tlmgr would update links and scripts in the 64 bit directory when it
updated similar files in other distributions. Most users won't notice the difference between
32 bit binaries and 64 bit binaries, so we're just trying to accommodate a few folks
who care. Let's not complicate the jobs of the
TeX Live maintainers by making them do something complicated with the Mac
portion of their scripts. 

Dick Koch