[yaml2obj][obj2yaml] - Add support for the architecture specific dynamic tags.

This allows tools to parse/dump the architecture specific tags
like DT_MIPS_*, DT_PPC64_* and DT_HEXAGON_*

Also fixes a bug in DynamicTags.def which was revealed in this patch.

Differential revision: https://reviews.llvm.org/D58667

llvm-svn: 354876