[babl] babl: add linear model meta data

[Øyvind "pippin" Kolås <ok src gnome org>]

commit 5cff52a0dcf5b2127b5c2e1c59df8d75f6befa2a
Author: Øyvind Kolås <pippin gimp org>
Date:   Tue Nov 27 00:25:19 2018 +0100

    babl: add linear model meta data

 babl/babl.h | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)
---
diff --git a/babl/babl.h b/babl/babl.h
index e76a72c..93cb615 100644
--- a/babl/babl.h
+++ b/babl/babl.h
@@ -297,10 +297,16 @@ enum _BablModelFlag
   BABL_MODEL_FLAG_RGB           = 1<<5,
   BABL_MODEL_FLAG_CMYK          = 1<<6,
   BABL_MODEL_FLAG_INVERTED      = 1<<7,
-  BABL_MODEL_FLAG_NONLINEAR     = 1<<8,
-  BABL_MODEL_FLAG_PERCEPTUAL    = 1<<9,
+
+  BABL_MODEL_FLAG_LINEAR        = 1<<8,
+  BABL_MODEL_FLAG_NONLINEAR     = 1<<9,
+  BABL_MODEL_FLAG_PERCEPTUAL    = 1<<10,
 };
 
+/* linear, nonlinear and perceptual could occupy two bits with a decidated 0,
+ * but we do not have a lack of bits in this bit pattern so leave it be.
+ */
+
 BablModelFlag babl_model_get_flags (const Babl *model);
 
 /**