Change check-lint to use golangci-lint (#3465)

golint is deprecated. The author of the code no longer supports the
codebase. golangci-lint is faster than golint, and is in use by other
opa repositories (e.g. Gatekeeper).

This commit changes tools.go to reference golangci (so it ends up in
vendor) and modifies check-lint to use golangci instead.

Breaking API Changes:

- plugins/rest/rest.go: Fix typo "AllowInsureTLS" -> "AllowInsecureTLS"
- storage/errors.go: Removed unused IndexingNotSupportedErr

Signed-off-by: Will Beason <willbeason@google.com>

util/backoff.go

@@ -22,7 +22,7 @@ func Backoff(base, max, jitter, factor float64, retries int) time.Duration {
 		return 0
 	}
 
-	backoff, max := float64(base), float64(max)
+	backoff, max := base, max
 	for backoff < max && retries > 0 {
 		backoff *= factor
 		retries--

util/hashmap_test.go

@@ -2,6 +2,7 @@
 // Use of this source code is governed by an Apache2
 // license that can be found in the LICENSE file.
 
+// nolint: goconst // string duplication is for test readability.
 package util
 
 import (