Add back Manifest::targets_mut

It is needed by cargo-c, it was removed in df5cb70

src/cargo/core/manifest.rs

@@ -431,6 +431,10 @@ impl Manifest {
  pub fn targets(&self) -> &[Target] {
  &self.targets
  }
+ // It is used by cargo-c, please do not remove it
+ pub fn targets_mut(&mut self) -> &mut [Target] {
+ &mut self.targets
+ }
  pub fn version(&self) -> &Version {
  self.package_id().version()
  }