net/url: fix stale RFC 3986 links

The URLs for RFC 3986 have been changed from:
  http://tools.ietf.org/html/rfc3986
to:
  https://datatracker.ietf.org/doc/html/rfc3986

Change-Id: I0662557d91bbb7de51d7ca4bc64e838741cd9074
Reviewed-on: https://go-review.googlesource.com/c/go/+/356429
Run-TryBot: Ian Lance Taylor <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Emmanuel Odeke <[email protected]>
Trust: Cherry Mui <[email protected]>

Author: 180909

src/net/url/url_test.go

@@ -1172,7 +1172,7 @@ var resolveReferenceTests = []struct {
 	{"http://foo.com/bar/baz", "quux/./dotdot/../dotdot/../dot/./tail/..", "http://foo.com/bar/quux/dot/"},
 
 	// Remove any dot-segments prior to forming the target URI.
-	// http://tools.ietf.org/html/rfc3986#section-5.2.4
+	// https://datatracker.ietf.org/doc/html/rfc3986#section-5.2.4
 	{"http://foo.com/dot/./dotdot/../foo/bar", "../baz", "http://foo.com/dot/baz"},
 
 	// Triple dot isn't special
@@ -1192,7 +1192,7 @@ var resolveReferenceTests = []struct {
 	{"http://foo.com/foo%2dbar/", "./baz-quux", "http://foo.com/foo%2dbar/baz-quux"},
 
 	// RFC 3986: Normal Examples
-	// http://tools.ietf.org/html/rfc3986#section-5.4.1
+	// https://datatracker.ietf.org/doc/html/rfc3986#section-5.4.1
 	{"http://a/b/c/d;p?q", "g:h", "g:h"},
 	{"http://a/b/c/d;p?q", "g", "http://a/b/c/g"},
 	{"http://a/b/c/d;p?q", "./g", "http://a/b/c/g"},
@@ -1218,7 +1218,7 @@ var resolveReferenceTests = []struct {
 	{"http://a/b/c/d;p?q", "../../g", "http://a/g"},
 
 	// RFC 3986: Abnormal Examples
-	// http://tools.ietf.org/html/rfc3986#section-5.4.2
+	// https://datatracker.ietf.org/doc/html/rfc3986#section-5.4.2
 	{"http://a/b/c/d;p?q", "../../../g", "http://a/g"},
 	{"http://a/b/c/d;p?q", "../../../../g", "http://a/g"},
 	{"http://a/b/c/d;p?q", "/./g", "http://a/g"},