Add check-pass test for issue 48109

Author: ldm0

src/test/ui/issues/issue-48109.rs

@@ -0,0 +1,14 @@
+// check-pass
+fn useful(i: usize) -> usize {
+    i
+}
+
+fn useful2(i: usize) -> usize {
+    i
+}
+
+fn main() {
+    for f in &[useful, useful2, |x| x] {
+        println!("{}", f(6));
+    }
+}