[PECOFF] Set a proper architecture type to references.
[PECOFF] Set a proper architecture type to references.

Relocations for x64 object files should have reference type of
KindArch::x86_64.

git-svn-id: f6089bf0e6284f307027cef4f64114ee9ebb0424@200183 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/lld,llvm-mirror/lld