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

This reverts commit 94a0cffe (r356764).

This change was originally committed in r356764, but then partially
reverted in r356777 due to "bad changes". This caused test failures
because the test changes committed along with the original change
were not reverted, so this change reverts the rest of the changes.

llvm-svn: 356811