[lbipng16] Fix "const" declaration info_ptr argument to png_get_eXIf_1() and the

num_exif argument to png_get_eXIf_1() (Github Issue 171).
diff --git a/png.h b/png.h
index 805891f..13e3415 100644
--- a/png.h
+++ b/png.h
@@ -2014,10 +2014,11 @@
     png_inforp info_ptr, png_bytep *exif));
 PNG_EXPORT(247, void, png_set_eXIf, (png_const_structrp png_ptr,
     png_inforp info_ptr, const png_bytep exif));
+
 PNG_EXPORT(248, png_uint_32, png_get_eXIf_1, (png_const_structrp png_ptr,
     png_const_inforp info_ptr, png_uint_32 *num_exif, png_bytep *exif));
 PNG_EXPORT(249, void, png_set_eXIf_1, (png_const_structrp png_ptr,
-    png_inforp info_ptr, png_uint_32 num_exif, const png_bytep exif));
+    png_inforp info_ptr, const png_uint_32 num_exif, const png_bytep exif));
 #endif
 
 #ifdef PNG_gAMA_SUPPORTED