CMake: Fix path to lrelease on debian.

Use a patch similar to qtbase/v5.2.0-alpha1~74^2^2~38 (Fix usr-move
workaround in the presence of multi-arch., 2013-08-30) to include
the appropriate calculation.

Task-number: QTBUG-36673
Change-Id: Iea0b6c64c5959d7d6dfce922c41031183c1c23d9
Reviewed-by: Lisandro Damián Nicanor Pérez Meyer <perezmeyer@gmail.com>
Reviewed-by: Stephen Kelly <stephen.kelly@kdab.com>