build: conditional creation of grl-net.pc files
build: conditional creation of grl-net.pc files

If libsoup is not available, then the grl-net library will not be built. Hence
we shall not create the grl-net.pc files. Otherwise we will compile plugins
that will not be able to be loaded.

Signed-off-by: Víctor Manuel Jáquez Leal <853e0dbb5ddd43a0f0483f24794ae05c4c52af91@igalia.com>

kyoushuu/grilo,MathieuDuponchelle/grilo,MathieuDuponchelle/grilo,grilofw/grilo,grilofw/grilo,jasuarez/grilo,GNOME/grilo,grilofw/grilo,kyoushuu/grilo,jasuarez/grilo,kyoushuu/grilo,MathieuDuponchelle/grilo,jasuarez/grilo,GNOME/grilo,kyoushuu/grilo