std.c (darwin) update to new opaque syntax
std.c (darwin) update to new opaque syntax

This was an undetected conflict between

76a195473dac059a842fed2a6ba581ca99947d2b and
95a37373e9f576854956c2909cc128b5b6388ec6

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