Introduce KDevClangPrivate shared lib

Authored by arrowd on Feb 15 2016, 9:48 PM.

Description

Introduce KDevClangPrivate shared lib

Merge all static libs into one shared library. This fixes ODR violations
we introduced when linking static libs both into the plugin + unit
tests.

Summary: Also link plugin to it, fix exports and make tests link to the shared lib.

Test Plan: test_problems is working now on Windows

Reviewers: kfunk, KDevelop

Subscribers: kfunk, mwolff, kdevelop-devel

Differential Revision: https://phabricator.kde.org/D772