add behavior test for `@enumToInt(enum(u1){x}.x)`
add behavior test for `@enumToInt(enum(u1){x}.x)`

closes #2737

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