Hide libevdev-openbsd from build ; see XXX in wayland/libevdev-openbsd/Makefile

Index: meson.build
--- meson.build.orig
+++ meson.build
@@ -77,7 +77,7 @@ dep_math = cc.find_library('m', required: false)
 dep_epoll = dependency('epoll-shim', required: false)
 dep_libxkbcommon = dependency('xkbcommon', required: false)
 config_h.set10('HAVE_LIBXKBCOMMON', dep_libxkbcommon.found())
-dep_libevdev = dependency('libevdev', required: false)
+dep_libevdev = dependency('libevdev-nonexistent', required: false)
 config_h.set10('HAVE_LIBEVDEV', dep_libevdev.found())
 
 if not get_option('liboeffis').disabled()
