The DW_AT_GNU_pubnames/pubtypes attributes are actually form
SEC_OFFSET from the beginning of the section so go ahead and emit
a label at the beginning of each one.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191710 91177308-0d34-0410-b5e6-96231b3b80d8