The pkgconfig file is generated at make-time, leading to absolute /usr/include & /usr/lib search paths.
The patch lets autoconf handle pkgconfig file subst, like other packages do.

Signed-off-by: Nicolas Thill <nico@openwrt.org>

- libkmod for programmatic control of Linux modules
- kmod for administrative control of Linux modules,
  symlinks for the familiar module-init-tools suite

Signed-off-by: Jeff Waugh <jdub@bethesignal.org>