message: tweak error message
diff: @@ -760,11 +760,11 @@ impl<'a, 'cfg> Context<'a, 'cfg> {
  if ret.is_empty() {
  if !unsupported.is_empty() {
  bail!(
  - "cannot produce {} for `{}` as the target `{}` \
  - does not support these crate types",
  - unsupported.join(", "),
  + "cannot compile `{}` package, because target `{}` \
  + does not support the `{}` crate types",
  unit.pkg,
  - self.target_triple()
  + self.target_triple(),
  + unsupported.join(", ")
  )
  }
  bail!(
  