[libpng16] Fixed some typos in comments.
diff --git a/pngset.c b/pngset.c
index 667a020..8eb5f6e 100644
--- a/pngset.c
+++ b/pngset.c
@@ -1578,7 +1578,7 @@
* It is possible for an indexed (color-type==3) PNG file to contain
* pixels with invalid (out-of-range) indexes if the PLTE chunk has
* fewer entries than the image's bit-depth would allow. We recover
- * from this gracefully by filling any incomplete palette with zeroes
+ * from this gracefully by filling any incomplete palette with zeros
* (opaque black). By default, when this occurs libpng will issue
* a benign error. This API can be used to override that behavior.
*/