[DwarfDebug] Skip entries to big for 16 bit size field in Dwarf < 5.
Nothing prevents entries from being bigger than the 16 bit size field in
Dwarf < 5. For entries that are too big, just emit an empty entry
instead of crashing.
This fixes PR41038.
Reviewers: probinson, aprantl, davide
Reviewed By: probinson
Differential Revision: https://reviews.llvm.org/D59518