add a test for returning a type that closes over a local const
add a test for returning a type that closes over a local const

closes #552

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