[yaml2obj][obj2yaml] - Support SHT_GNU_verdef (.gnu.version_d) section.

This patch adds support for parsing/dumping the .gnu.version section.

Description of the section is: https://refspecs.linuxfoundation.org/LSB_1.3.0/gLSB/gLSB/symverdefs.html

Differential revision: https://reviews.llvm.org/D58437

llvm-svn: 354574