[babl] babl: add meta data to RGBA model in core

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

commit 58f8c5d542292d85d2fb3930c1781cd737447b5c
Author: Øyvind Kolås <pippin gimp org>
Date:   Tue Nov 27 00:28:15 2018 +0100

    babl: add meta data to RGBA model in core

 babl/babl-core.c  | 3 +++
 babl/babl-model.c | 4 ++++
 2 files changed, 7 insertions(+)
---
diff --git a/babl/babl-core.c b/babl/babl-core.c
index aab809a..c551cb9 100644
--- a/babl/babl-core.c
+++ b/babl/babl-core.c
@@ -133,6 +133,9 @@ babl_core_init (void)
     babl_component_from_id (BABL_GREEN),
     babl_component_from_id (BABL_BLUE),
     babl_component_from_id (BABL_ALPHA),
+    "rgb",
+    "linear",
+    "alpha",
     NULL);
 
   /*
diff --git a/babl/babl-model.c b/babl/babl-model.c
index 7b41303..0eae215 100644
--- a/babl/babl-model.c
+++ b/babl/babl-model.c
@@ -160,6 +160,10 @@ babl_model_new (void *first_argument,
         {
           flags |= BABL_MODEL_FLAG_ALPHA;
         }
+      else if (!strcmp (arg, "linear"))
+        {
+          flags |= BABL_MODEL_FLAG_LINEAR;
+        }
       else if (!strcmp (arg, "nonlinear"))
         {
           flags |= BABL_MODEL_FLAG_NONLINEAR;