[babl] babl: set babl_rel_avg_error to a high value on NaN

[Øyvind Kolås <ok src gnome org>]

commit 1081ca43b78bc7779337eb313edd84553a3cab24
Author: Øyvind Kolås <pippin gimp org>
Date:   Mon Sep 25 22:46:21 2017 +0200

    babl: set babl_rel_avg_error to a high value on NaN
    
    In relation to bug #787441, if the sum of errors contain a nan the sum
    is nan, we return pi as a much higher than expected average error to
    indicate that this is not 0.0.

 babl/babl-util.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)
---
diff --git a/babl/babl-util.c b/babl/babl-util.c
index 9b08913..23c1513 100644
--- a/babl/babl-util.c
+++ b/babl/babl-util.c
@@ -91,10 +91,12 @@ babl_rel_avg_error (const double *imgA,
   for (i = 0; i < samples; i++)
     error += fabs (imgA[i] - imgB[i]);
 
-  if (error >= 0.000001)
+  if (error >= 0.0000001)
     error /= samples;
-  else
+  else if (error <= 0.0)
     error = 0.0;
+  else
+    error = M_PI;
 
   return error;
 }