inline the at_eof() call when possible
inline the at_eof() call when possible

THis might seem like a microoptimization, but in most ases, at_eof will
either return a constant (false for &[u8] and &str, true for
CompleteByteSlice and CompleteStr) or a member of the input type,
so that would be an indirection VS a function call

Geal/nom,Keruspe/nom