[babl] babl: make powf approximation yield 0 for negatives

[Øyvind Kolås <ok src gnome org>]

commit 83ccc6d027554527d84b9883c08145fce8193454
Author: Øyvind Kolås <pippin gimp org>
Date:   Sun Sep 17 20:24:16 2017 +0200

    babl: make powf approximation yield 0 for negatives

 babl/babl-trc.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)
---
diff --git a/babl/babl-trc.c b/babl/babl-trc.c
index 7d9f82f..7524ef8 100644
--- a/babl/babl-trc.c
+++ b/babl/babl-trc.c
@@ -93,10 +93,11 @@ static inline float _babl_trc_gamma_to_linear (const Babl *trc_, float value)
     {
       return babl_polynomial_eval (&trc->poly_gamma_to_linear, value);
     }
-  else
+  else if (value > 0.0f)
     {
       return powf (value, trc->gamma);
     }
+  return 0.0f;
 }
 
 static inline float _babl_trc_gamma_from_linear (const Babl *trc_, float value)
@@ -107,10 +108,11 @@ static inline float _babl_trc_gamma_from_linear (const Babl *trc_, float value)
     {
       return babl_polynomial_eval (&trc->poly_gamma_from_linear, value);
     }
-  else
+  else if (value > 0.0f)
     {
       return powf (value, trc->rgamma);
     }
+  return 0.0f;
 }
 
 static inline void _babl_trc_gamma_to_linear_buf (const Babl *trc_, const float *in, float *out, int in_gap, 
int out_gap, int components, int count)