[DWARFv5] Support DW_FORM_strp in the .debug_line header.
[DWARFv5] Support DW_FORM_strp in the .debug_line header.

Supporting this form in .debug_line.dwo will be done as a follow-up.

Differential Revision: https://reviews.llvm.org/D33155

git-svn-id: f6089bf0e6284f307027cef4f64114ee9ebb0424@317607 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/lld,llvm-mirror/lld