[gvfs] metadata: Use static keyword for private function

[Ondrej Holy <oholy src gnome org>]

commit e417487975ac99ca935fabf2907150b6d618f197
Author: Ondrej Holy <oholy redhat com>
Date:   Thu Sep 21 19:48:42 2017 +0200

    metadata: Use static keyword for private function
    
    More warnings are printed when building thanks to meson port. Let's add
    static keyword for private metafile_key_lookup_iter function in order
    to prevent the following warning:
    warning: no previous prototype for ‘metafile_key_lookup_iter’
    
    https://bugzilla.gnome.org/show_bug.cgi?id=786149

 metadata/metabuilder.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/metadata/metabuilder.c b/metadata/metabuilder.c
index a8c8e3e..f45d20a 100644
--- a/metadata/metabuilder.c
+++ b/metadata/metabuilder.c
@@ -344,7 +344,7 @@ metafile_set_mtime (MetaFile    *file,
   file->last_changed = mtime;
 }
 
-GSequenceIter *
+static GSequenceIter *
 metafile_key_lookup_iter (MetaFile *file,
                           const char *key)
 {