Android: Fix -D QT_OPENGL_FORCE_SHADER_DEFINES option

On Windows a space between -D and QT_OPENGL_FORCE_SHADER_DEFINES
seems to be needed.

Task-number: QTBUG-32576

Change-Id: I61599d2963c53b0c6146617b39b374c523556586
Reviewed-by: Sergio Ahumada <sergio.ahumada@digia.com>