[cogl/cogl-1.20] Fix compiler warnings

[Emmanuele Bassi <ebassi src gnome org>]

commit 15b952e03ef4f221a5029d37c44e0410c98f31f2
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Wed Jun 10 14:10:34 2015 +0100

    Fix compiler warnings
    
    Simple enumeration checks.

 cogl/driver/gl/cogl-attribute-gl.c           |    2 ++
 cogl/driver/gl/cogl-pipeline-fragend-fixed.c |    3 +++
 cogl/driver/gl/cogl-util-gl.c                |    5 +++++
 3 files changed, 10 insertions(+), 0 deletions(-)
---
diff --git a/cogl/driver/gl/cogl-attribute-gl.c b/cogl/driver/gl/cogl-attribute-gl.c
index b23b0ab..34ddb55 100644
--- a/cogl/driver/gl/cogl-attribute-gl.c
+++ b/cogl/driver/gl/cogl-attribute-gl.c
@@ -82,6 +82,8 @@ toggle_builtin_attribute_enabled_cb (int bit_num, void *user_data)
       case COGL_ATTRIBUTE_NAME_ID_NORMAL_ARRAY:
         cap = GL_NORMAL_ARRAY;
         break;
+      default:
+        g_assert_not_reached ();
       }
     if (enabled)
       GE (context, glEnableClientState (cap));
diff --git a/cogl/driver/gl/cogl-pipeline-fragend-fixed.c b/cogl/driver/gl/cogl-pipeline-fragend-fixed.c
index 7e461f9..55b0956 100644
--- a/cogl/driver/gl/cogl-pipeline-fragend-fixed.c
+++ b/cogl/driver/gl/cogl-pipeline-fragend-fixed.c
@@ -208,6 +208,9 @@ _cogl_pipeline_fragend_fixed_add_layer (CoglPipeline *pipeline,
         case COGL_TEXTURE_TYPE_RECTANGLE:
           gl_target = GL_TEXTURE_RECTANGLE_ARB;
           break;
+
+        default:
+          g_assert_not_reached ();
         }
 
       _cogl_set_active_texture_unit (unit_index);
diff --git a/cogl/driver/gl/cogl-util-gl.c b/cogl/driver/gl/cogl-util-gl.c
index 814621a..a50a8a3 100644
--- a/cogl/driver/gl/cogl-util-gl.c
+++ b/cogl/driver/gl/cogl-util-gl.c
@@ -139,6 +139,11 @@ _cogl_gl_util_get_texture_target_string (CoglTextureType texture_type,
       target_string = "2DRect";
       tex_coord_swizzle = "st";
       break;
+
+    default:
+      target_string = "Unknown";
+      tex_coord_swizzle = NULL;
+      g_assert_not_reached ();
     }
 
   if (target_string_out)