Problems building 2.5.1 on AIX

[Roy Smith]

I've got an AIX-5.2 box that I'm trying to build Python 2.5.1 on.  
Configure dies pretty much immediately:

hasty:Python-2.5.1$ CC=/usr/vacpp/bin/cc_r ./configure --without-gcc
checking MACHDEP... aix5
checking EXTRAPLATDIR... 
checking for --without-gcc... yes
checking for gcc... cc
checking for C compiler default output file name... configure: error: C 
compiler cannot create executables
See `config.log' for more details.

I get the same result with or without the --without-cgg.  There's nothing 
obvious in config.log (not that I can ever make much sense out of the 
gibberish configure generates).

Any ideas?