shortcuts-plugin: Fix shortcuts-editor include
This accidently works on distros that follows FHS because libxfce4util
has -I${includedir}/xfce4
as its Cflags and libxfce4kbd-private-3
requires
that. In FHS distros includedir
is mostly the same everywhere, but this is
not the case in NixOS.
In libxfce4kbd-private-3.pc
we have -I${includedir}/xfce4/libxfce4kbd-private-3
,
let's adjust the xfce-shortcuts-editor.h
include to follow that.
Fixes: #295 (closed)