[llvm-readobj] Separate `Symbol Version` dumpers into `LLVM style` and `GNU style`

[llvm-readobj] Separate `Symbol Version` dumpers into `LLVM style` and `GNU style`

Summary:
Currently, llvm-readobj can dump symbol version sections only in LLVM style. In this patch, I would like to separate these dumpers into GNU style and
LLVM style for future implementation.

Reviewers: grimar, jhenderson, mattd, rupprecht

Reviewed By: rupprecht

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59186

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@356764 91177308-0d34-0410-b5e6-96231b3b80d8