build-style qmake: detect qmake w/o qtchooser

Instead of relying on qtchooser to provide the link to the qmake
binary for Qt4 or Qt5 test for either version and use that.
Sometimes qtchooser can fail if e.g. a package was built with Qt4
and after that another package with Qt5 without zapping the masterdir.

common/build-style/qmake.sh

@@ -2,7 +2,19 @@
 # This helper is for templates using Qt4/Qt5 qmake.
 #
 do_configure() {
-	qmake ${configure_args} \
+	local qmake
+	if [ -x "/usr/lib/qt5/bin/qmake" ]; then
+		# Qt5 qmake
+		qmake="/usr/lib/qt5/bin/qmake"
+	fi
+	if [ -x "/usr/lib/qt/bin/qmake" ]; then
+		# Qt4 qmake
+		qmake="/usr/lib/qt/bin/qmake"
+	fi
+	if [ -z "${qmake}" ]; then
+		msg_error "${pkgver}: Could not find qmake - missing in hostdepends?\n"
+	fi
+	${qmake} ${configure_args} \
 		PREFIX=/usr \
 		LIB=/usr/lib \
 		QMAKE_CC=$CC QMAKE_CXX=$CXX QMAKE_LINK=$CXX \