qt5-build.eclass: adjust configure options for >=5.15

Upstream has removed the -qt-xcb, -system-xcb, -xkb, -xcb-xinput
switches [1] in 5.15 and 6.0.

1. https://code.qt.io/cgit/qt/qtbase.git/commit/?h=5.15&id=60588e1a

Signed-off-by: Jimi Huotari <chiitoo@gentoo.org>
Signed-off-by: Andreas Sturmlechner <asturm@gentoo.org>

eclass/qt5-build.eclass

@@ -569,7 +569,11 @@ qt5_base_configure() {
 		-no-freetype -no-harfbuzz
 		-no-openssl -no-libproxy
 		-no-xcb-xlib
-		-no-xcb-xinput -no-xkbcommon # bug 672340
+
+		# bug 672340
+		-no-xkbcommon
+		$([[ ${QT5_MINOR_VERSION} -lt 15 ]] && echo -no-xcb-xinput)
+		$([[ ${QT5_MINOR_VERSION} -ge 15 ]] && echo -no-bundled-xcb-xinput)
 
 		# cannot use -no-gif because there is no way to override it later
 		#-no-gif
@@ -617,7 +621,7 @@ qt5_base_configure() {
 
 		# disable undocumented X11-related flags, override in qtgui
 		# (not shown in ./configure -help output)
-		-no-xkb
+		$([[ ${QT5_MINOR_VERSION} -lt 15 ]] && echo -no-xkb)
 
 		# always enable session management support: it doesn't need extra deps
 		# at configure time and turning it off is dangerous, see bug 518262