cmake: Fix building debug with release libclang

Parts of QC cannot be linked against a release build of clangTooling
libs and vice versa when building on Windows.
Check whether the provided libs match the current build mode and
disable respective parts if necessary.
Re-use this information to decide whether unittest should be build
or not.

Change-Id: Ibc2aab0d7886e78ebbf8f15a43152efad49f1eff
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/clangrefactoring/CMakeLists.txt

@@ -1,6 +1,6 @@
 add_qtc_plugin(ClangRefactoring
   BUILD_DEFAULT OFF
-  CONDITION TARGET libclang
+  CONDITION TARGET libclang AND QTC_CLANG_BUILDMODE_MATCH
   DEPENDS ClangSupport CPlusPlus
   PLUGIN_DEPENDS Core CppTools TextEditor ClangPchManager
   SOURCES ${TEST_SOURCES}