Avoid writing to errs().
Avoid writing to errs().

We should write to ErrorOS instead. Normaly, *ErrorOS == errs(),
but they can be different if LLD is embedded.

git-svn-id: f6089bf0e6284f307027cef4f64114ee9ebb0424@275525 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/lld,llvm-mirror/lld