macho: specify -install_name as full dylib's name
macho: specify -install_name as full dylib's name

This then allows for proper resolution of names via runpath search
path list, i.e., `-rpath @loader_path` will correctly resolve
to `@rpath/libxxx.dylib (...)` in the linked binary.

andrewrk/zig,zig-lang/zig,andrewrk/zig,raulgrell/zig,raulgrell/zig,zig-lang/zig,raulgrell/zig,zig-lang/zig,raulgrell/zig,raulgrell/zig