rust: serde: enable the core_c_str feature

Signed-off-by: Miguel Ojeda <[email protected]>

Author: ojeda

rust/serde/lib.rs

@@ -92,6 +92,8 @@
 
 ////////////////////////////////////////////////////////////////////////////////
 
+#![feature(core_c_str)]
+
 // Serde types in rustdoc of other crates get linked to here.
 #![doc(html_root_url = "https://docs.rs/serde/1.0.156")]
 // Support using Serde without the standard library!