[PCH] When visiting preprocessed entities, make it possible to avoid deserializing

preprocessed entities that are #included in the range that we are interested.

This is useful when we are interested in preprocessed entities of a specific file, e.g
when we are annotating tokens. There is also an optimization where we cache the last
result of PreprocessingRecord::getPreprocessedEntitiesInRange and we re-use it if
there is a call with the same range as before.

rdar://10313365

llvm-svn: 142887