migrate codebase to ..= inclusive range patterns

These were stabilized in March 2018's #47813, and are the Preferred Way
to Do It going forward (q.v. #51043).

src/test/compile-fail/refutable-pattern-errors.rs

@@ -9,10 +9,10 @@
 // except according to those terms.
 
 
-fn func((1, (Some(1), 2...3)): (isize, (Option<isize>, isize))) { }
+fn func((1, (Some(1), 2..=3)): (isize, (Option<isize>, isize))) { }
 //~^ ERROR refutable pattern in function argument: `(_, _)` not covered
 
 fn main() {
-    let (1, (Some(1), 2...3)) = (1, (None, 2));
+    let (1, (Some(1), 2..=3)) = (1, (None, 2));
     //~^ ERROR refutable pattern in local binding: `(_, _)` not covered
 }