qt: use qtchooser to make it the default version.

srcpkgs/qt/INSTALL

@@ -0,0 +1,6 @@
+case "$ACTION" in
+post)
+	# qt4 by default via qtchooser.
+	ln -sf /etc/xdg/qtchooser/4.conf etc/xdg/qtchooser/default.conf
+	;;
+esac

srcpkgs/qt/template

@@ -1,7 +1,7 @@
 # Template file for 'qt'
 pkgname=qt
 version=4.8.6
-revision=6
+revision=7
 _distname=qt-everywhere-opensource-src
 patch_args="-Np1"
 wrksrc=${_distname}-${version}
@@ -21,6 +21,7 @@ makedepends="
  sqlite-devel alsa-lib-devel tiff-devel libmng-devel libxshmfence-devel
  libSM-devel gtk+-devel libmysqlclient-devel>=5.5.27 postgresql-libs-devel
  pulseaudio-devel"
+depends="qtchooser"
 
 pre_configure() {
 	sed -i "s|-O2|${CXXFLAGS}|" mkspecs/common/{g++,gcc}-base.conf