windeployqt: Add --release-with-debug-info option..

The option can be used for Qt builds with
-force-debug-info -release .
For those, deployment fails with "Unable to find the platform
plugin." since the DLLs are detected as debug-built. If windeployqt is
extended to actually read Qt configuration information, the value can be
obtained from there.

Task-number: QTBUG-42072
Change-Id: If8b4a0e41821b5f0f4b7023b1b9a3d49e50628a1
Reviewed-by: Jarred Nicholls <jarred.nicholls@gmail.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@theqtcompany.com>