[metacity] workspace: fix build warnings

[Alberts Muktupāvels <muktupavels src gnome org>]

commit 196b92ab3a3472927d212860ab4aa1b7718b0dd3
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Sun Sep 20 18:03:53 2015 +0300

    workspace: fix build warnings

 src/core/workspace.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)
---
diff --git a/src/core/workspace.c b/src/core/workspace.c
index 9b34215..c97b6e1 100644
--- a/src/core/workspace.c
+++ b/src/core/workspace.c
@@ -788,7 +788,7 @@ meta_workspace_get_onxinerama_region (MetaWorkspace *workspace,
 }
 
 #ifdef WITH_VERBOSE_MODE
-static char *
+static const gchar *
 meta_motion_direction_to_string (MetaMotionDirection direction)
 {
   switch (direction)
@@ -801,6 +801,8 @@ meta_motion_direction_to_string (MetaMotionDirection direction)
       return "Left";
     case META_MOTION_RIGHT:
       return "Right";
+    default:
+      break;
     }
 
   return "Unknown";
@@ -839,6 +841,8 @@ meta_workspace_get_neighbor (MetaWorkspace      *workspace,
     case META_MOTION_DOWN:
       layout.current_row += 1;
       break;
+    default:
+      break;
     }
 
   if (layout.current_col < 0)