[babl] Fix warning: -Wsign-compare babl-fish-path

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

commit 89f6909ee75de2e7204ec18a92b2966a0b72b185
Author: Axel Viala <axel viala darnuria eu>
Date:   Fri Mar 25 15:36:16 2022 +0100

    Fix warning: -Wsign-compare babl-fish-path

 babl/babl-fish-path.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/babl/babl-fish-path.c b/babl/babl-fish-path.c
index bf88ab633..c51d46158 100644
--- a/babl/babl-fish-path.c
+++ b/babl/babl-fish-path.c
@@ -287,7 +287,7 @@ static void measure_timings(void)
    LUT_LOG("BABL_LUT_UNUSED_LIMIT=%.1f\n", lut_unused_minutes_limit);
 
    LUT_LOG("measuring lut timings          \n");
-   for (int p = 0; p < sizeof (pairs)/sizeof(pairs[0]);p++)
+   for (size_t p = 0; p < sizeof (pairs)/sizeof(pairs[0]);p++)
    {
      int source_bpp = pairs[p][0];
      int dest_bpp = pairs[p][1];