getRawCommentForDeclNoCacheImpl: linemarkers between between comment and declaration

Hi,

when looking for comments attached to a declaration, the
implementation aborts if (among other things) it finds a preprocessor
macro.
The problem with that is that when parsing a preprocessed file there
might be linemarkers like this:

# 4 "bug.c" 3 4
static inline
# 4 "bug.c"
         void fn(void);

Here, "static inline" was expanded from a macro. GCC seems to add
linemarkers if the macro comes from a system header.

I think that as long as the line markers just update the line
information of the current file and are not entering/leaving a
different file it should be okay to attach the comment to the
declaration.

That might be more complicated though because right now the check is
being done using a simple text search:

if (Text.find_first_of(";{}#@") != StringRef::npos) {
  printf("preproc\n");
  return nullptr;
}

What do you think?

Thanks
Michael