Add regression test for jump to def links on items with generics

tests/rustdoc/link-on-path-with-generics.rs

@@ -0,0 +1,14 @@
+// This test ensures that paths with generics still get their link to their definition
+// correctly generated.
+
+//@ compile-flags: -Zunstable-options --generate-link-to-definition
+#![crate_name = "foo"]
+
+//@ has 'src/foo/link-on-path-with-generics.rs.html'
+
+pub struct Soyo<T>(T);
+pub struct Saya;
+
+//@ has - '//pre[@class="rust"]//a[@href="#9"]' 'Soyo'
+//@ has - '//pre[@class="rust"]//a[@href="#10"]' 'Saya'
+pub fn bar<T>(s: Soyo<T>, x: Saya) {}