[elfabi] Add support for reading DT_NEEDED from binaries

This patch gives elfabi the ability to read DT_NEEDED entries from ELF binaries
to populate NeededLibs in TextAPI's ELFStub.

Differential Revision: https://reviews.llvm.org/D55852

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@351592 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed