Don't hide the first ELF symbol.

The first symbol on ELF is dummy, but it has a defined content and readelf
normally displays it. With this change llvm-readobj also displays it and we
can check that llvm-mc output is correct according to the standard.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183337 91177308-0d34-0410-b5e6-96231b3b80d8