.pc files

[Havoc Pennington <hp redhat com>]

Hi,

To get pkg-config rolling, I want to commit .pc.in files to glib, pango,
and GTK+ CVS. Also the files have to be added to AC_OUTPUT, and
Makefile.am installs them as data. But basically the patch doesn't
break anything in there now.

This patch will NOT change the configure.in to use pkg-config; that
can come later. The change only installs the .pc file so other
apps/libs can use them, so we can start testing pkg-config, move
gnome-libs to it, see what features are missing, etc.

Havoc