Change some constants to uppercase names
Change some constants to uppercase names

This silences a warning, and more closely matches the original Lua C
names.

green-panther/rust-lua,tempbottle/rust-lua,beatgammit/rust-lua,beatgammit/rust-lua,green-panther/rust-lua,tempbottle/rust-lua,kballard/rust-lua,kballard/rust-lua