Since a34e81ab [1], 'xkbcommon_support' is under
'src/platformsupport/input', and will not be defined when building
with -no-libinput, and as such, 'xkbcommon_support-private' added in
'src/plugins/platforms/xcb/xcb_qpa_lib.pro' will be unknown.
1. https://code.qt.io/cgit/qt/qtbase.git/commit/?h=5.14&id=a34e81ab
Change-Id: I79563b329623651b462b8fedcfb59ef5f2c2e52a
Gentoo-bug: https://bugs.gentoo.org/699110
Suggested-by: Petr Zima <zima@matfyz.cz>
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
2e7c83ea38