[llvm-readobj][yaml2obj] Support SHT_LLVM_SYMPART, SHT_LLVM_PART_EHDR and SHT_LLVM_PART_PHDR
See http://lists.llvm.org/pipermail/llvm-dev/2019-February/130583.html
and D60242 for the lld partition feature.
This patch:
* Teaches yaml2obj to parse the 3 section types.
* Teaches llvm-readobj/llvm-readelf to dump the 3 section types.
There is no test for SHT_LLVM_DEPENDENT_LIBRARIES in llvm-readobj. Add
it as well.
Reviewed By: thakis
Differential Revision: https://reviews.llvm.org/D67228
llvm-svn: 371157