Log message:
Pullup ticket #4713 - requested by hiramatsu
x11/xproto: packaging fix

Revisions pulled up:
- x11/xproto/builtin.mk                                         1.5

---
   Module Name:	pkgsrc
   Committed By:	hiramatsu
   Date:		Tue May 12 13:59:11 UTC 2015

   Modified Files:
   	pkgsrc/x11/xproto: builtin.mk

   Log message:
   Converted to use mk/buildlink3/pkgconfig-builtin.mk to determine
   the version of system installed xproto.