Implement IMAGE_REL_AMD64_SECREL for RuntimeDyldCOFFX86_64

lldb on Windows uses the ExecutionEngine for expression evaluation
and hits the llvm_unreachable due to this relocation. Thus, implement
the relocation and add a test to verify it's function.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@348904 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed