Drop Copy/Clone from git_merge_file_result

I don't feel comfortable making this copy, since it could accidentally
lead to creating multiple copies, which could then be confused as the
memory of these needs to be managed.

Author: ehuss

libgit2-sys/lib.rs

@@ -1373,7 +1373,6 @@ pub struct git_merge_file_options {
 }
 
 #[repr(C)]
-#[derive(Clone, Copy)]
 pub struct git_merge_file_result {
     pub automergeable: c_uint,
     pub path: *const c_char,

src/merge.rs

@@ -395,7 +395,7 @@ impl<'repo> Binding for MergeFileResult<'repo> {
         }
     }
     fn raw(&self) -> raw::git_merge_file_result {
-        self.raw
+        unimplemented!()
     }
 }