Builder|Debian: Further updates to .deb package building rules

No separate Assimp build needed. qtchooser is used for running qmake.
Note that these are currently used only for the Launchpad packages.

distrib/debian/control.template

@@ -2,7 +2,7 @@ Source: ${Package}
 Section: universe/games
 Priority: optional
 Maintainer: Jaakko Keränen <jaakko.keranen@iki.fi>
-Build-Depends: debhelper (>= 8.0.0), python, libsdl2-dev, libsdl2-mixer-dev, libxrandr-dev, libxxf86vm-dev, qt5-qmake, qtbase5-dev, libqt5opengl5-dev, libqt5x11extras5-dev, zlib1g-dev, libfluidsynth-dev, libncurses5-dev, cmake (>= 3.1)
+Build-Depends: debhelper (>= 8.0.0), python, libsdl2-dev, libsdl2-mixer-dev, libxrandr-dev, libxxf86vm-dev, qtchooser, qt5-qmake, qtbase5-dev, libqt5opengl5-dev, libqt5x11extras5-dev, zlib1g-dev, libfluidsynth-dev, libncurses5-dev, cmake (>= 3.1)
 Standards-Version: 3.9.3
 Homepage: http://dengine.net/
 Vcs-Git: https://github.com/skyjake/Doomsday-Engine.git

distrib/debian/rules

@@ -1,16 +1,14 @@
 #!/usr/bin/make -f
 APPNAME := doomsday
-ASSIMP_DIR := $(shell if [ -e ../doomsday/external/assimp ]; then echo ../doomsday/external/assimp; \
-                else echo doomsday/external/assimp; fi)
 
 builddir:
 	mkdir -p builddir
 
 builddir/Makefile: builddir
-	cd $(ASSIMP_DIR) && cmake -G "Unix Makefiles" && make -j2
-	cd builddir && cmake -DCMAKE_BUILD_TYPE=Release \
+	cd builddir && QTCHOOSER_RUNTOOL=qmake QT_SELECT=5 cmake \
+		-DQMAKE=qtchooser \
+		-DCMAKE_BUILD_TYPE=Release \
 		-DDENG_BUILD=`../build_number.py --print` \
-		-DASSIMP_DIR=$(ASSIMP_DIR) \
 		../../doomsday
 
 build: build-arch build-indep