gitian: make linux qt intermediate deterministic

A qt installation date snuck into the host utils (lrelease etc)
This doesn't affect the end product, so no dependency version bump.

It also doesn't explain why gavin's and mine build is different

contrib/gitian-descriptors/qt-linux.yml

@@ -40,6 +40,7 @@ script: |
   tar xzf qt-everywhere-opensource-src-4.6.4.tar.gz
   cd qt-everywhere-opensource-src-4.6.4
   QTBUILDDIR=$(pwd)
+  sed 's/TODAY=`date +%Y-%m-%d`/TODAY=2011-01-30/' -i configure
 
   # Need to build 4.6-versioned host utilities as well (lrelease/qrc/lupdate/...)
   ./configure -prefix $INSTALLPREFIX -confirm-license -release -opensource -no-qt3support -no-multimedia -no-audio-backend -no-phonon -no-phonon-backend -no-declarative -no-script -no-scripttools -no-javascript-jit -no-webkit -no-svg -no-xmlpatterns -no-sql-sqlite -no-nis -no-cups -no-iconv -no-dbus -no-gif -no-libtiff -no-opengl -nomake examples -nomake demos -nomake docs