[elfabi] Introduce tool for ELF TextAPI
Follow up for D53051
This patch introduces the tool associated with the ELF implementation of
TextAPI (previously llvm-tapi, renamed for better distinction). This
tool will house a number of features related to enalysis and
manipulation of shared object's exposed interfaces. The first major
feature for this tool is support for producing binary stubs that are
useful for compile-time linking of shared objects. This patch introduces
beginnings of support for reading binary ELF objects to work towards
- elfabi tool.
- support for reading architecture from a binary ELF file into an ELFStub.
- Support for writing .tbe files.
Differential Revision: https://reviews.llvm.org/D55352