fix release-with-debug-info build with MSVC

Make debug/release runtime decision dependent of qbs.enableDebugCode
instead of qbs.debugInformation.

Change-Id: Ifc3b134f8979f2196ef58d8b1603104859f62736
Reviewed-by: Thomas Epting <thomas.epting@stryker.com>
Reviewed-by: Jake Petroules <jake.petroules@petroules.com>