[babl] extensions: fix up some lingering references to babl_alpha_avoid_zero

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

commit db232e24a9714bee854ae1f2c7a40fbb2f66b895
Author: Øyvind Kolås <pippin gimp org>
Date:   Thu Jun 13 17:08:57 2019 +0200

    extensions: fix up some lingering references to babl_alpha_avoid_zero

 extensions/float.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/extensions/float.c b/extensions/float.c
index b25870f..839924c 100644
--- a/extensions/float.c
+++ b/extensions/float.c
@@ -44,7 +44,7 @@ conv_rgbaF_linear_rgbAF_nonlinear (const Babl    *conversion,
    while (n--)
      {
        float alpha = fsrc[3];
-       float used_alpha = babl_alpha_avoid_zero (alpha);
+       float used_alpha = babl_epsilon_for_zero_float (alpha);
        *fdst++ = babl_trc_from_linear (trc[0], *fsrc++) * used_alpha;
        *fdst++ = babl_trc_from_linear (trc[1], *fsrc++) * used_alpha;
        *fdst++ = babl_trc_from_linear (trc[2], *fsrc++) * used_alpha;
@@ -66,7 +66,7 @@ conv_rgbaF_linear_rgbAF_perceptual (const Babl    *conversion,
    while (n--)
      {
        float alpha = fsrc[3];
-       float used_alpha = babl_alpha_avoid_zero (alpha);
+       float used_alpha = babl_epsilon_for_zero (alpha);
        *fdst++ = babl_trc_from_linear (trc_srgb, *fsrc++) * used_alpha;
        *fdst++ = babl_trc_from_linear (trc_srgb, *fsrc++) * used_alpha;
        *fdst++ = babl_trc_from_linear (trc_srgb, *fsrc++) * used_alpha;