message: Fix typo in map_feature_as_c_define macro
diff: @@ -56,7 +56,8 @@ macro_rules! map_feature_as_c_define {
  ($feature:expr, $c_define:ident, $accumulator:ident) => {
  #[cfg(feature = $feature)]
  {
  - let _ = write!($accumulator
  + use std::fmt::Write;
  + let _ = write!($accumulator,
  r#"
  // The `{feature}` feature has been enabled for this build.
  #define {define}
  