Handle IMAGE_REL_AMD64_ADDR32NB in RuntimeDyldCOFF

Summary:
IMAGE_REL_AMD64_ADDR32NB relocations are currently set to zero in all cases.
This patch sets the relocation to the correct value when possible and shows an error when not.

Reviewers: enderby, lhames, compnerd

Reviewed By: compnerd

Subscribers: LepelTsmok, compnerd, martell, llvm-commits

Differential Revision: https://reviews.llvm.org/D30709

llvm-svn: 325700