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

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@142887 91177308-0d34-0410-b5e6-96231b3b80d8