message: Move the codemap tests into a #[cfg(test)] module
  Summary: Should have always been done this way.
diff: @@ -413,6 +413,10 @@ impl Display for FileSpanLoc {
  }
  }
  +#[cfg(test)]
  +mod test {
  + use super::*;
  +
  #[test]
  fn test_codemap() {
  let source = "abcd\nefghij\nqwerty";
  @@ -514,3 +518,4 @@ fn test_multibyte() {
  LineCol { line: 1, column: 1 }
  );
  }
  +}
  