[libpng16] Only mark text chunks as written after successfully writing them.
diff --git a/example.c b/example.c
index ad5fc70..9075e57 100644
--- a/example.c
+++ b/example.c
@@ -932,7 +932,7 @@
     */
 
    /* Once we write out the header, the compression type on the text
-    * chunks gets changed to PNG_TEXT_COMPRESSION_NONE_WR or
+    * chunk gets changed to PNG_TEXT_COMPRESSION_NONE_WR or
     * PNG_TEXT_COMPRESSION_zTXt_WR, so it doesn't get written out again
     * at the end.
     */