pkg-config support for biarch

[Steven Munroe]

I am current working a project to port a package to ppc64. There is an
existing ppc32 port for this package.

The problem I see is that when I run:

	pkg-config --libs glib-2.0 gthread-2.0

I get 

	-pthread -L/opt/gnome/lib -lgthread-2.0 -lglib-2.0

which is wrong for a powerpc64 target. It should be:

	-pthread -L/opt/gnome/lib64 -lgthread-2.0 -lglib-2.0

This is --version 20. Lot of projects use libtool and pkg-config as park
of configure. And many of these projects fail to build for powerpc64. 

64-bit PowerPC is fully biarch and supports 32-bit and 64-bit
applications an libraries equally well. But 32-bit is the default. The
distros build 32- and 64-bit bit versions of most packages so we
normally full set of libraries in <prefix>/lib and <prefix>/lib64.

Is there a way to tell pkg-config to pick the <prefix>/lib64 set and
ignore the <prefix>/lib ?