internal/testprotos/legacy: rename and regenerate

Avoid dots and dashes in the directory to avoid issues on
build systems that cannot support them well.

Change-Id: I7ea5e6ce0b16c7158c7e53bcf5c3c1a334fe4718
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/214342
Reviewed-by: Damien Neil <dneil@google.com>
diff --git a/internal/impl/legacy_message.go b/internal/impl/legacy_message.go
index ac96e71..80220a2 100644
--- a/internal/impl/legacy_message.go
+++ b/internal/impl/legacy_message.go
@@ -267,7 +267,7 @@
 	if t.Kind() == reflect.Ptr {
 		t = t.Elem()
 	}
-	return aberrantDeriveFullName(t)
+	return AberrantDeriveFullName(t)
 }
 
 func aberrantAppendField(md *filedesc.Message, goType reflect.Type, tag, tagKey, tagVal string) {