Allow cloning DataDescriptor (#3377)

cranelift/module/src/data_context.rs

@@ -10,7 +10,7 @@ use std::string::String;
 use std::vec::Vec;
 
 /// This specifies how data is to be initialized.
-#[derive(PartialEq, Eq, Debug)]
+#[derive(Clone, PartialEq, Eq, Debug)]
 pub enum Init {
     /// This indicates that no initialization has been specified yet.
     Uninitialized,
@@ -38,6 +38,7 @@ impl Init {
 }
 
 /// A description of a data object.
+#[derive(Clone)]
 pub struct DataDescription {
     /// How the data should be initialized.
     pub init: Init,