[gimp] libgimp: fix return values in g_return_val_if_fail() statements

[Michael Natterer <mitch src gnome org>]

commit e7dc21d7952f6087c3903d21a724087a4a3bc910
Author: Michael Natterer <mitch gimp org>
Date:   Thu Sep 24 21:32:33 2015 +0200

    libgimp: fix return values in g_return_val_if_fail() statements
    
    GLib master fixed the missing warnings since whatever GCC version.

 libgimp/gimpdrawablepreview.c   |    2 +-
 libgimp/gimpimagecolorprofile.c |    4 ++--
 libgimp/gimpzoompreview.c       |    2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/libgimp/gimpdrawablepreview.c b/libgimp/gimpdrawablepreview.c
index 11859c5..a95f5d9 100644
--- a/libgimp/gimpdrawablepreview.c
+++ b/libgimp/gimpdrawablepreview.c
@@ -645,7 +645,7 @@ gimp_drawable_preview_new_from_drawable_id (gint32 drawable_ID)
 gint32
 gimp_drawable_preview_get_drawable_id (GimpDrawablePreview *preview)
 {
-  g_return_val_if_fail (GIMP_IS_DRAWABLE_PREVIEW (preview), NULL);
+  g_return_val_if_fail (GIMP_IS_DRAWABLE_PREVIEW (preview), -1);
 
   return GIMP_DRAWABLE_PREVIEW_GET_PRIVATE (preview)->drawable_ID;
 }
diff --git a/libgimp/gimpimagecolorprofile.c b/libgimp/gimpimagecolorprofile.c
index 806d7a3..2b0b458 100644
--- a/libgimp/gimpimagecolorprofile.c
+++ b/libgimp/gimpimagecolorprofile.c
@@ -79,7 +79,7 @@ gimp_image_set_color_profile (gint32            image_ID,
   gint          length = 0;
 
   g_return_val_if_fail (profile == NULL || GIMP_IS_COLOR_PROFILE (profile),
-                        NULL);
+                        FALSE);
 
   if (profile)
     {
@@ -158,7 +158,7 @@ gimp_image_convert_color_profile (gint32                     image_ID,
   gint          length = 0;
 
   g_return_val_if_fail (profile == NULL || GIMP_IS_COLOR_PROFILE (profile),
-                        NULL);
+                        FALSE);
 
   if (profile)
     {
diff --git a/libgimp/gimpzoompreview.c b/libgimp/gimpzoompreview.c
index 8c61bb1..8b68287 100644
--- a/libgimp/gimpzoompreview.c
+++ b/libgimp/gimpzoompreview.c
@@ -883,7 +883,7 @@ gimp_zoom_preview_new_with_model (GimpDrawable  *drawable,
 gint32
 gimp_zoom_preview_get_drawable_id (GimpZoomPreview *preview)
 {
-  g_return_val_if_fail (GIMP_IS_ZOOM_PREVIEW (preview), NULL);
+  g_return_val_if_fail (GIMP_IS_ZOOM_PREVIEW (preview), -1);
 
   return GIMP_ZOOM_PREVIEW_GET_PRIVATE (preview)->drawable_ID;
 }