add doc(include) to the save-analysis test

src/test/run-make/save-analysis/extra-docs.md

+Extra docs for this struct.

src/test/run-make/save-analysis/foo.rs

@@ -12,6 +12,7 @@
 #![feature(box_syntax)]
 #![feature(rustc_private)]
 #![feature(associated_type_defaults)]
+#![feature(external_doc)]
 
 extern crate graphviz;
 // A simple rust project
@@ -461,3 +462,6 @@ fn next(&mut self) -> Option<Self::Item> {
 trait Foo {
     type Bar = FrameBuffer;
 }
+
+#[doc(include="extra-docs.md")]
+struct StructWithDocs;