Improve the implementation of libclang's token-annotation logic for

entities in the preprocessing record. Previously, we would only end up
getting the first token of a preprocessing record annotated
correctly. For example, given

  #include "foo.h"

we would only get the '#' annotated as an inclusion directive; the
'include' and '"foo.h"' tokens would be given the general 'processing
directive' annotation.

Now, we get proper annotations for entities in the preprocessing
record.

llvm-svn: 117001