make Parser::parse_foreign_item() return a foreign item or error

closes #54441

src/test/parse-fail/duplicate-visibility.rs

@@ -10,7 +10,7 @@
 
 // compile-flags: -Z parse-only
 
-// error-pattern:expected one of `(`, `fn`, `static`, `type`, or `}` here
+// error-pattern:expected one of `(`, `fn`, `static`, or `type`
 extern {
     pub pub fn foo();
 }

src/test/ui/macros/issue-54441.rs

@@ -0,0 +1,13 @@
+#![feature(macros_in_extern)]
+
+macro_rules! m {
+    () => {
+        let //~ ERROR expected
+    };
+}
+
+extern "C" {
+    m!();
+}
+
+fn main() {}

src/test/ui/macros/issue-54441.stderr

@@ -0,0 +1,14 @@
+error: expected one of `crate`, `fn`, `pub`, `static`, or `type`, found `let`
+  --> $DIR/issue-54441.rs:5:9
+   |
+LL | #![feature(macros_in_extern)]
+   | - expected one of `crate`, `fn`, `pub`, `static`, or `type` here
+...
+LL |         let //~ ERROR expected
+   |         ^^^ unexpected token
+...
+LL |     m!();
+   |     ----- in this macro invocation
+
+error: aborting due to previous error
+