Build with QT5 on Debian-based systems using contrib/debian

contrib/debian/changelog

@@ -1,3 +1,9 @@
+bitcoin (0.14.1-trusty3) trusty; urgency=medium
+
+  * Build with qt5 if we are on a non-Ubuntu (ie non-Unity) distro.
+
+ -- Matt Corallo (BlueMatt) <matt@mattcorallo.com>  Thu, 04 May 2017 17:13:00 -0400
+
 bitcoin (0.14.1-trusty2) trusty; urgency=medium
 
   * Bump minimum boost version in deps.

contrib/debian/control

@@ -18,8 +18,8 @@ Build-Depends: debhelper,
  libboost-thread1.48-dev | libboost-thread-dev (>> 1.47),
  libboost-test1.48-dev | libboost-test-dev (>> 1.47),
  libboost-chrono1.48-dev | libboost-chrono-dev (>> 1.47),
- qt4-qmake,
+ qt4-qmake, libqt4-dev,
- libqt4-dev,
+ qttools5-dev-tools, qttools5-dev,
  libqrencode-dev,
  libprotobuf-dev, protobuf-compiler,
  python,

contrib/debian/rules

@@ -12,10 +12,12 @@ override_dh_auto_clean:
 	if [ -f Makefile ]; then $(MAKE) distclean; fi
 	rm -rf Makefile.in aclocal.m4 configure src/Makefile.in src/bitcoin-config.h.in src/build-aux src/qt/Makefile.in src/qt/test/Makefile.in src/test/Makefile.in
 
+QT=$(shell dpkg-vendor --derives-from Ubuntu && echo qt4 || echo qt5)
+
 # Yea, autogen should be run on the source archive, but I like doing git archive
 override_dh_auto_configure:
 	./autogen.sh
-	./configure --without-miniupnpc --with-gui=qt4
+	./configure --without-miniupnpc --with-gui=$(QT)
 
 override_dh_auto_test:
 	make check