Allow compiling with 3.5
use SrcMgr::C_ExternCSystem for the builtin includes
cleanup FindClang.cmake
Fix #22: Make sure we ignore all -Wunused-value warnings
Add ClangUtils::lookupFunctionsInClass()
Fix looking up Q_PRIVATE_SLOTS

Qt headers often use undefined private classes there which breaks the
run of the tool -> fall back to string based comparison instead of
generating a method in the macro
Make sure output for Q_PRIVATE_SLOTS is correct
Fix tests