[ELF] - Added testcase for testing visibility of weak_odr symbols.

This is relative to "Bug 36166 - tools/gold/X86/comdat.ll is failing only on Debian Unstable" (PR36166).
Something changed in newer versions of gold and now together with gold-plugin
there is an issue shown in PR, symbol may get wrong visibility.

LLD works fine, but we have no testcase for the same use case, patch adds it.

Differential revision: https://reviews.llvm.org/D43193

llvm-svn: 325874