net-im/telegram-desktop: Chase Qt5 update

This unfortunately makes use of the Qt private API, so it has to be
rebuilt with each Qt update.

Fix the qt5 flavor when building on a live system that also has Qt6
installed. If both Qt5 and Qt6 were installed, it would default to
using Qt6.

net-im/telegram-desktop/Makefile

 PORTNAME=	telegram-desktop
 DISTVERSION=	5.0.4
+PORTREVISION=	1
 CATEGORIES=	net-im
 MASTER_SITES=	https://github.com/${GH_ACCOUNT}/${GH_PROJECT}/releases/download/v${DISTVERSION}/
 DISTNAME=	tdesktop-${DISTVERSION}-full
@@ -71,7 +72,8 @@ USE_GL=		gl
 USE_GNOME=	glib20 glibmm26 introspection
 USE_XORG=	x11 xcb xcomposite xdamage xext xfixes xrandr xrender xtst
 
-CMAKE_ARGS=	-DTDESKTOP_API_ID=${TELEGRAM_API_ID} -DTDESKTOP_API_HASH=${TELEGRAM_API_HASH}
+CMAKE_ARGS=	-DTDESKTOP_API_ID=${TELEGRAM_API_ID} -DTDESKTOP_API_HASH=${TELEGRAM_API_HASH} \
+		-DQT_VERSION_MAJOR=${FLAVOR:S/qt//}
 CMAKE_ON=	DESKTOP_APP_USE_PACKAGED DESKTOP_APP_DISABLE_CRASH_REPORTS \
 		DESKTOP_APP_DISABLE_SCUDO \
 		DESKTOP_APP_DISABLE_WAYLAND_INTEGRATION