While trying to recompile a package that pulled in "gd-devel" as a build
requirement, I got a compile error about -ljpeg missing. After checking, I see
that gd is linked against many libraries, but that its devel package doesn't
require their devel packages in turn as it should :

$ /usr/bin/gdlib-config --libs
-lXpm -lX11 -ljpeg -lfreetype -lpng12 -lz -lm

$ rpm -qp --requires gd-devel-2.0.33-1.i386.rpm
/bin/sh
gd = 2.0.33-1
rpmlib(CompressedFileNames) <= 3.0.4-1
rpmlib(PayloadFilesHavePrefix) <= 4.0-1

From the output above, the devel package should also have :
Requires: xorg-x11-devel, libjpeg-devel, freetype-devel, libpng-devel, zlib-devel