[shotwell] photos: Fix build with vala git

[Rico Tzschichholz <ricotz src gnome org>]

commit 91f0804130cb87aaf0cdfe1c58b2740c4748fedd
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Sat Oct 8 17:27:59 2016 +0200

    photos: Fix build with vala git
    
    Default values must be at least as accessible as the methods which require
    them.

 src/photos/PhotoMetadata.vala |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/photos/PhotoMetadata.vala b/src/photos/PhotoMetadata.vala
index c2dcdff..814ea6b 100644
--- a/src/photos/PhotoMetadata.vala
+++ b/src/photos/PhotoMetadata.vala
@@ -215,7 +215,7 @@ public class PhotoMetadata : MediaMetadata {
         AT_LEAST_DEFAULT_DOMAIN
     }
     
-    private const PrepareInputTextOptions PREPARE_STRING_OPTIONS =
+    public const PrepareInputTextOptions PREPARE_STRING_OPTIONS =
         PrepareInputTextOptions.INVALID_IS_NULL
         | PrepareInputTextOptions.EMPTY_IS_NULL
         | PrepareInputTextOptions.STRIP