amd64 as target

[Chuck Robey <chuckr chuckr org>]

I'm having a heck of a time trying to get glib and gtk to compile nicely 
for the amd64.  The configure script keeps on finding the binaries in 
/usr/bin and using them  to make decisions, ones that aren't always 
correct... you see, I have to cater to two platform needs, one is the 
323 bit one that you're all very familiar with, but the other one needs 
-m64, and isn't really very compatible withthe -m32 bit mode.

The use of binaries in /usr/bin is confusing me more, I need someone to 
lay out the playing field in 2 different ways: one, let me know, please, 
how the binaries (glib-something in /usr/bin) figure in the 
configuration) and what the right set of switches is in configure to get 
me *both* of the two modes I need to cater to.

You see, I tried using "env CFLAGS=-m64 configure 
--libdir=/usr/local/lib64" but it fails, telliiimg me that the gcc can't 
create executeables.  That was for the 64 bit stuff.  For the 32 bit 
stuff, it's bringing in /usr/X11R6/lib64, which is completely wrong for 
the 32 bit mode.

Ahh, I'm losing my mind over autoconf.  Just tell me if there's a 
"magic" phrase I should be  using for the x86_64.

BTW, word to the wise:  on many older packages, I can get them to work 
by copying the config.sub and config.guess from the latest autoconf 
(which knows the x86_64 well enough, especially after I hacked it just a 
bit more that way).