rustc_span: avoid unnecessary cloning in byte_pos_to_line_and_col
rustc_span: avoid unnecessary cloning in byte_pos_to_line_and_col

graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust