Add missing #![doc(auto_cfg)] attribute in rustdoc tests

Author: GuillaumeGomez

src/test/rustdoc/doc-auto-cfg.rs

@@ -1,6 +1,8 @@
 #![feature(doc_auto_cfg)]
 #![crate_name = "foo"]
 
+#![doc(auto_cfg)]
+
 // @has foo/fn.foo.html
 // @has - '//*[@class="item-info"]/*[@class="stab portability"]' 'non-meowmeow'
 #[cfg(not(meowmeow))]

src/test/rustdoc/doc-cfg-hide.rs

@@ -1,6 +1,7 @@
 #![crate_name = "oud"]
 #![feature(doc_auto_cfg, doc_cfg, doc_cfg_hide)]
 
+#![doc(auto_cfg)]
 #![doc(cfg_hide(feature = "solecism"))]
 
 // @has 'oud/struct.Solecism.html'

src/test/rustdoc/doc-cfg-implicit-gate.rs

@@ -1,6 +1,8 @@
 // compile-flags:--cfg feature="worricow"
 #![crate_name = "xenogenous"]
 
+#![doc(auto_cfg)]
+
 // @has 'xenogenous/struct.Worricow.html'
 // @count   - '//*[@class="stab portability"]' 0
 #[cfg(feature = "worricow")]

src/test/rustdoc/doc-cfg-implicit.rs

@@ -1,6 +1,8 @@
 #![crate_name = "funambulism"]
 #![feature(doc_auto_cfg, doc_cfg)]
 
+#![doc(auto_cfg)]
+
 // @has 'funambulism/struct.Disorbed.html'
 // @count   - '//*[@class="stab portability"]' 1
 // @matches - '//*[@class="stab portability"]' 'crate feature disorbed'

src/test/rustdoc/doc_auto_cfg_nested_impl.rs

@@ -4,6 +4,8 @@
 #![crate_type = "lib"]
 #![crate_name = "foo"]
 
+#![doc(auto_cfg)]
+
 pub struct S;
 pub trait MyTrait1 {}
 pub trait MyTrait2 {}