pkgsrc's pkg-config not finding stuff?

[Dario Niedermann <dnied%tiscali.it@localhost>]

After removing Slackware's bundled X.org and installing pkgsrc's own
modular Xorg, I'm now trying to make a package for the Synaptics
TouchPad driver that pkgsrc lacks.

I can build the source code "manually" all right, but when I try to make
a package of it, I find that pkgsrc-wrapped pkg-config doesn't find the
stuff it should, and the build breaks.

Relevant part of the log:

-----BEGIN LOG-----
[...]
checking for pkg-config... 
/usr/pkgsrc/x11/xf86-input-synaptics/work/.tools/bin/pkg-config
checking pkg-config is at least version 0.9.0... yes
Package xorg-macros was not found in the pkg-config search path.
Perhaps you should add the directory containing `xorg-macros.pc'
to the PKG_CONFIG_PATH environment variable
No package 'xorg-macros' found
checking which optional backends will be build... eventcomm
checking if XINPUT is defined... no
checking for XORG... no
configure: error: Package requirements (xorg-server xproto ) were not met:

No package 'xorg-server' found
No package 'xproto' found

Consider adjusting the PKG_CONFIG_PATH environment variable if you
installed software in a non-standard prefix.

Alternatively, you may set the environment variables XORG_CFLAGS
and XORG_LIBS to avoid the need to call pkg-config.
See the pkg-config man page for more details.
*** Error code 1

Stop.
bmake: stopped in /usr/pkgsrc/x11/xf86-input-synaptics
*** Error code 1

Stop.
bmake: stopped in /usr/pkgsrc/x11/xf86-input-synaptics
Exit 1
[pkgsrc/x11/xf86-input-synaptics]# echo $PKG_CONFIG_PATH
/usr/pkg/lib/pkgconfig:/usr/pkg/share/pkgconfig:/usr/local/lib/pkgconfig:/usr/lib/pkgconfig
[pkgsrc/x11/xf86-input-synaptics]# which pkg-config
/usr/pkg/bin/pkg-config
[pkgsrc/x11/xf86-input-synaptics]# /usr/pkg/bin/pkg-config xorg-server
[pkgsrc/x11/xf86-input-synaptics]# /usr/pkg/bin/pkg-config xproto
[pkgsrc/x11/xf86-input-synaptics]# /usr/pkg/bin/pkg-config quuuuuuuuuuuuuux
Exit 1
[pkgsrc/x11/xf86-input-synaptics]#
-----END LOG-----


An 'env' instruction I temporarily added to the original 'configure'
script shows that the $PKG_CONFIG_PATH variable in configure's
environment contains all the right directories, but pkgsrc-wrapped
pkg-config seems to ignore it.

How do I get it to find the stuff that IS installed?

Here's the package's Makefile, made via url2pkg & pkglint, then
modified by hand:

-----BEGIN MAKEFILE-----
# $NetBSD$
#

DISTNAME=       xf86-input-synaptics-synaptics-1.2-branch
PKGNAME=        xf86-input-synaptics-1.2.2
CATEGORIES=     x11
MASTER_SITES=   
http://cgit.freedesktop.org/xorg/driver/xf86-input-synaptics/snapshot/

MAINTAINER=     dnied%tiscali.it@localhost
HOMEPAGE=       http://cgit.freedesktop.org/xorg/driver/xf86-input-synaptics/
COMMENT=        This is the Synaptics TouchPad driver for the modular Xorg 
server
LICENSE=        mit

PKG_DESTDIR_SUPPORT=    user-destdir
BUILD_DEPENDS+=         xorg-util-macros>=1.1:../../devel/xorg-util-macros
DEPENDS+=               libXrandr-[0-9]*:../libXrandr
#still not sure DEPENDS+=xf86-input-mouse-[0-9]*:../xf86-input-mouse

GNU_CONFIGURE=          yes
USE_TOOLS+=             pkg-config aclocal automake m4 autom4te autoheader 
autoconf autoreconf

PKGCONFIG_OVERRIDE+=    xorg-synaptics.pc.in

pre-configure:
        cd ${WRKSRC} && ./autogen.sh

CONFIGURE_ARGS+=--prefix=/usr/pkg --sysconfdir=/etc/X11 --localstatedir=/var

.include "../../mk/bsd.pkg.mk"
-----END MAKEFILE-----