centralize setting of "CONFIG += shared dll" for libraries

centralize setting of "CONFIG += shared dll" for libraries

"dll" and "shared" set each other, but too late to actually test for it
in the project files, so include both.
note that this will slightly modify the build of some of our imported qt
solutions.

Change-Id: I0bd4f41a68fd160f8e87eb0a0fa66096fe70ef3e
Reviewed-by: Maurice Kalinowski <maurice.kalinowski@nokia.com>