cmake: fix setting DBUS_*_CONFIG_FILE on non win32 platform
Reported at #375 (comment 1243881)
Fixup for bug: https://bugs.freedesktop.org/show_bug.cgi?id=89280
Edited by Ralf Habacker
Reported at #375 (comment 1243881)
Fixup for bug: https://bugs.freedesktop.org/show_bug.cgi?id=89280