When building modular-xorg-server, the configure script fails to detect printproto even when it is installed. There is some code in the xorg-server package which can use printproto, even though the package builds without error when printproto is 'missing'. modular-xorg-libs pulls in printproto automatically, so it seems reasonable to allow xorg-server to use printproto, yes? Anyway, I find that adding printproto/buildlink3.mk to the Makefile for modular-xorg-server fixes the problem. If there really is a problem here, that is. I don't know what difference it makes, one way or the other.