Building rpms on AMD64

[Per Steinar Iversen <PerSteinar Iversen adm hio no>]

I tried this question on fedora-list yesterday, and got a number of 
messages from other users with the same problem, but no resolution.
Perhaps this list is a better place to ask?


A silly question: How does one build or rebuild src rpms under x86_64?

On a freshly installed FC3 (full install) nearly everything fails to build 
as configure looks at the wrong X11 libraries. As an example, rebuilding 
mozilla:

$ rpmbuild --rebuild mozilla-1.7.5-3.src.rpm
...lines deleted...
checking GLIB_LIBS...   -lglib-2.0
configure: error:  Could not find the following X libraries:  -lX11 -lXext -lXt
error: Bad exit status from /var/tmp/rpm-tmp.13288 (%build)

Modifying the spec-file to add a line like this cures the problem:

--x-libraries=/usr/X11R6/lib64

But this is probably too crude - what is the proper incantation to make 
rpmbuild understand where the X11 libraries are placed on x86_64?

-psi