Merge pull request #71 from arielb1/all-the-world-is-an-intel

ignore doctest of `extern "stdcall"` on non-x86

Author: steveklabnik

src/items.md

@@ -416,6 +416,7 @@ modifier.
 extern fn new_i32() -> i32 { 0 }
 
 // Declares an extern fn with "stdcall" ABI
+# #[cfg(target_arch = "x86_64")]
 extern "stdcall" fn new_i32_stdcall() -> i32 { 0 }
 ```