rustc_fluent_macro::fluent_messages uses CARGO_PKG_NAME instead of CARGO_CRATE_NAME

[lolbinarycat]

the crate name is an identifier used by rustc, and cannot contain hyphens.

the package name is only used by cargo, and can contain hyphens.

the issue is at compiler/rustc_fluent_macro/fluent.rs.html:81

[lolbinarycat]

this causes problems if anyone tries to make a compiler plugin with hyphens in the package name.