Define DbiStreamBuilder::addSectionMap.

This change enables LLD to construct a Section Map stream in a PDB file.
I do not understand all these fields in the Section Map yet, but it seems
like a copy of a COFF section header in another format.

With this patch, DbiStreamBuilder can emit a Section Map which
llvm-pdbdump can dump.

Differential Revision: https://reviews.llvm.org/D26112

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@285606 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed