x11-toolkits/qt5-gui: unbreak with libglvnd

> Building package for qt5-gui-5.14.2

pkg-static: Unable to access file /wrkdirs/usr/ports/x11-toolkits/qt5-gui/work/stage/usr/local/include/qt5/QtKmsSupport/5.14.2/QtKmsSupport/private/qkmsdevice_p.h:No such file or directory
pkg-static: Unable to access file /wrkdirs/usr/ports/x11-toolkits/qt5-gui/work/stage/usr/local/include/qt5/QtKmsSupport/QtKmsSupport:No such file or directory
pkg-static: Unable to access file /wrkdirs/usr/ports/x11-toolkits/qt5-gui/work/stage/usr/local/include/qt5/QtKmsSupport/QtKmsSupportDepends:No such file or directory
pkg-static: Unable to access file /wrkdirs/usr/ports/x11-toolkits/qt5-gui/work/stage/usr/local/include/qt5/QtKmsSupport/QtKmsSupportVersion:No such file or directory
pkg-static: Unable to access file /wrkdirs/usr/ports/x11-toolkits/qt5-gui/work/stage/usr/local/include/qt5/QtKmsSupport/qtkmssupportversion.h:No such file or directory
pkg-static: Unable to access file /wrkdirs/usr/ports/x11-toolkits/qt5-gui/work/stage/usr/local/lib/cmake/Qt5KmsSupport/Qt5KmsSupportConfig.cmake:No such file or directory
pkg-static: Unable to access file /wrkdirs/usr/ports/x11-toolkits/qt5-gui/work/stage/usr/local/lib/cmake/Qt5KmsSupport/Qt5KmsSupportConfigVersion.cmake:No such file or directory
pkg-static: Unable to access file /wrkdirs/usr/ports/x11-toolkits/qt5-gui/work/stage/usr/local/lib/qt5/libQt5KmsSupport.a:No such file or directory
pkg-static: Unable to access file /wrkdirs/usr/ports/x11-toolkits/qt5-gui/work/stage/usr/local/lib/qt5/libQt5KmsSupport.prl:No such file or directory
pkg-static: Unable to access file /wrkdirs/usr/ports/x11-toolkits/qt5-gui/work/stage/usr/local/lib/qt5/mkspecs/modules/qt_lib_kms_support_private.pri:No such file or directory

• Error code 1