[mach-o]: Support deprecated -seg1addr alias for -image_base
[mach-o]: Support deprecated -seg1addr alias for -image_base

Because NO LINKER MAY CHANGE. EVER. Even if it's a complete rewrite
from scratch.

git-svn-id: f6089bf0e6284f307027cef4f64114ee9ebb0424@217572 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/lld,llvm-mirror/lld