libtime locale values

[saosebastiao]

libtime currently uses what appears to be en_US.UTF8 locale definitions hardcoded into the strftime/strptime functions.

https://github.com/rust-lang/rust/blob/master/src/libtime/lib.rs#L512-L548

These values should be derived from system-level locale definitions, such that they can be used in different locales correctly. However, I'm not sure how this would work for different operating systems/architectures. Is there a cross-platform standard practice that should guide the design of these parsing/formatting functions?

[gsingh93]

This should probably be closed or moved to https://github.com/rust-lang/time

[steveklabnik]

Done! time-rs/time#65