Fix unknown-crate when using self-profile with rustdoc

... by removing a duplicate `crate_name` field in `interface::Config`,
making it clear that rustdoc should be passing it to `config::Options`
instead.

compiler/rustc_session/src/session.rs

@@ -1338,7 +1338,7 @@ pub fn build_session(
 
         let profiler = SelfProfiler::new(
             directory,
-            sopts.crate_name.as_ref().map(|s| &s[..]),
+            sopts.crate_name.as_deref(),
             &sopts.debugging_opts.self_profile_events,
         );
         match profiler {