internal/descfmt: rename from typefmt

The name descfmt more closely matches the fact that this package
provides pretty-printing for descriptors.

Change-Id: I11b0e4a0302962ee7bbf315fb259d050847cadbb
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/178479
Reviewed-by: Damien Neil <dneil@google.com>
diff --git a/internal/legacy/extension.go b/internal/legacy/extension.go
index 216cb4e..1f53f1b 100644
--- a/internal/legacy/extension.go
+++ b/internal/legacy/extension.go
@@ -9,10 +9,10 @@
 	"reflect"
 	"sync"
 
+	"google.golang.org/protobuf/internal/descfmt"
 	ptag "google.golang.org/protobuf/internal/encoding/tag"
 	pimpl "google.golang.org/protobuf/internal/impl"
 	ptype "google.golang.org/protobuf/internal/prototype"
-	pfmt "google.golang.org/protobuf/internal/typefmt"
 	pvalue "google.golang.org/protobuf/internal/value"
 	pref "google.golang.org/protobuf/reflect/protoreflect"
 	preg "google.golang.org/protobuf/reflect/protoregistry"
@@ -276,4 +276,4 @@
 func (x *extensionType) New() pref.Value                      { return x.new() }
 func (x *extensionType) ValueOf(v interface{}) pref.Value     { return x.valueOf(v) }
 func (x *extensionType) InterfaceOf(v pref.Value) interface{} { return x.interfaceOf(v) }
-func (x *extensionType) Format(s fmt.State, r rune)           { pfmt.FormatDesc(s, r, x.Descriptor()) }
+func (x *extensionType) Format(s fmt.State, r rune)           { descfmt.FormatDesc(s, r, x.Descriptor()) }