[mach-o] keep Windows library happy.
[mach-o] keep Windows library happy.

&v[v.size()] may be invalid C++.

git-svn-id: f6089bf0e6284f307027cef4f64114ee9ebb0424@220115 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/lld,llvm-mirror/lld