DebugInfo: Do not use the DWARF Version for the .debug_pubnames or .debug_pubtypes version field

Summary:
LLVM would generate DWARF with version 3 in the .debug_pubname and
.debug_pubtypes version fields.  This would lead SGI dwarfdump to fail
parsing the DWARF with (in the instance of .debug_pubnames) would exit
with:
dwarfdump ERROR:  dwarf_get_globals: DW_DLE_PUBNAMES_VERSION_ERROR (123)

This fixes PR16950.

Reviewers: echristo, dblaikie

Reviewed By: echristo

CC: cfe-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D1454