Fix the QT build on Qt 5.3 or later to use the windeployqt tool
to copy the rquired Qt files into the runtime directory

Qt 5.2 is broken as windeployqt doesn't take the required --release flag

Also fix the passing of GCC_DLL and GPGERROR_DLL into config.pri so
that the Qt build copies the required files instead of the entire
gnutls bin dir twice (the variables expanded to nothing).

Add support for autodetection of Qt 5.3.0 with msvc2013

Change-Id: I1e9c70a5ff5d1fdfdce88ba15d324f1899c8129c
Reviewed-on: https://code.wireshark.org/review/2734
Reviewed-by: Pascal Quantin <pascal.quantin@gmail.com>
Tested-by: Graham Bloice <graham.bloice@trihedral.com>
Reviewed-by: Graham Bloice <graham.bloice@trihedral.com>
Reviewed-by: Anders Broman <a.broman58@gmail.com>