Postgres 8.3.1 configure fails on Solaris 10 using gcc 3.4.3 and building for 64 bit

I've been using Postgres for years on FreeBSD boxen with very
little problems.

My company have now given me a big Sun box with 4 AMD64 processors
to told me to port my system to it. The problem is that I am not
fluent in Solaris!

I am adding CFLAGS='-m64' to the configure line, but gcc and ld
seem strangely reluctant to use 64bit components, with the configure
script failing to run the test compile with the error:

wrong ELF class: ELFCLASS32

I've used 'crle' to set the paths, but it appears that only controls
the loading, not the linking.

So I would like to know just what parameters to hand to configure
to make this work.

I had a look on the 'buildfarm' page, and saw that emperor_moth was
nominaly the same type of build. But I can't see there where a 64 bit
build is being requested.

I'm probably missing somethig simple!

Regards,
Harry.