lint: make the non_camel_case_types lint work with scripts without a upper/lowercase distinction.
rustc: add a lint to enforce uppercase statics.
auto merge of #7523 : huonw/rust/uppercase-statics-lint, r=cmr

Adds a lint for `static some_lowercase_name: uint = 1;`. Warning by default since it causes confusion, e.g. `static a: uint = 1; ... let a = 2;` => `error: only refutable patterns allowed here`.