Fix min_ident_chars: add test for long params in trait method

declaration

Author: t-webber

tests/ui/min_ident_chars.rs

@@ -145,4 +145,5 @@ trait D {
     fn f(g: i32);
     //~^ min_ident_chars
     //~| min_ident_chars
+    fn long(long: i32);
 }