Make file type filtering a lot faster.

We do this by avoiding using a RegexSet (*sigh*). In particular, file
type matching has much simpler semantics than gitignore files, so we don't
actually need to care which file type matched. Therefore, we can get away
with a single regex with a giant alternation.

src/args.rs

@@ -367,7 +367,7 @@ impl RawArgs {
             types.select(ty);
         }
         for ty in &self.flag_type_not {
-            types.select_not(ty);
+            types.negate(ty);
         }
         Ok(())
     }