windeployqt: Add compiler runtime.

For MSVC, add the redistributable installers.
For MinGW, add the runtime libraries.

Task-number: QTBUG-28766

Change-Id: Ia1a32d14d8a924ab72cd6fc1ef87f4fd8d9454f2
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Reviewed-by: Kai Koehne <kai.koehne@digia.com>