[BOLT] Testcase to repro R_X86_64_REX_GOTPCRELX bug

Add a new testcase that reproduces a bug when BOLTing current
trunk LLD bootstrapped with trunk clang. This makes it official
that we do not support this transformation but are working on
it. When the support is ready, XFAIL should be removed.

Reviewed By: maksfb, Amir, yota9

Differential Revision: https://reviews.llvm.org/D125843