build: Various srcdir != builddir fixes
build: Various srcdir != builddir fixes

gnome-ostree does it by default.

https://bugzilla.gnome.org/show_bug.cgi?id=706132

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