workaround doc generation error on non-darwin platforms

Author: jbatez

library/std/src/os/darwin/objc.rs

@@ -1,8 +1,11 @@
 //! Defines types and macros for Objective-C interoperability.
+//!
+//! This module re-exports all the items in [`core::os::darwin::objc`].
 
 #![unstable(feature = "darwin_objc", issue = "145496")]
 
-// The `no_inline`-attribute is required to make the documentation of all targets available.
-// See https://github.com/rust-lang/rust/pull/57808#issuecomment-457390549 for more information.
-#[doc(no_inline)]
+// We can't document this automatically since we generate documentation for this module
+// on every platform but `core::os::darwin` isn't available on every platform.
+// We just mention it in the module documentation above instead.
+#[cfg(not(doc))]
 pub use core::os::darwin::objc::*;