c: Put global parser variables into c namespace
tests: Update test runner commentary
Fix tkTurnCPPTokensIntoCIds() to preserve token flags etc.
Add pre-parse pass to collect typedefs

This collects information on typedefs from all found header files (even
those that will be filtered out) in order to improve the type cast
disambiguation during the main C parsing pass.

This helps in cases where a typedef is used before being declared (can only
happen in #define bodies) or when a typedef comes from some #included
header whose constructs won't be parsed by the main C parsing pass.