proto: move T->*T wrappers from internal/scalar to proto

Usage of these is pervasive in code which works with proto2, and proto2
will be with us for a long, long time to come. Move them to the proto
package.

Change-Id: I1b2e57429fd5a8f107a848a4492d20c27f304bd7
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/185543
Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
diff --git a/proto/reset_test.go b/proto/reset_test.go
index b9ad5b7..0f2f8cd 100644
--- a/proto/reset_test.go
+++ b/proto/reset_test.go
@@ -7,7 +7,6 @@
 import (
 	"testing"
 
-	"google.golang.org/protobuf/internal/scalar"
 	"google.golang.org/protobuf/proto"
 
 	testpb "google.golang.org/protobuf/internal/testprotos/test"
@@ -15,7 +14,7 @@
 
 func TestReset(t *testing.T) {
 	m := &testpb.TestAllTypes{
-		OptionalSfixed64:       scalar.Int64(5),
+		OptionalSfixed64:       proto.Int64(5),
 		RepeatedInt32:          []int32{},
 		RepeatedFloat:          []float32{1.234, 5.678},
 		MapFixed64Fixed64:      map[uint64]uint64{5: 7},