[gegl] webp-load: use signed capable return type when returning -1

[Øyvind Kolås <ok src gnome org>]

commit 4528bbe3e24377b75c44aa49522ec33ebe1dcaa5
Author: Øyvind Kolås <pippin gimp org>
Date:   Sat Sep 30 01:53:55 2017 +0200

    webp-load: use signed capable return type when returning -1

 operations/external/webp-load.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/operations/external/webp-load.c b/operations/external/webp-load.c
index 7e34608..cd6e63a 100644
--- a/operations/external/webp-load.c
+++ b/operations/external/webp-load.c
@@ -105,7 +105,7 @@ read_from_stream (GInputStream *stream,
   return read;
 }
 
-static gsize
+static glong
 decode_from_stream (GInputStream *stream,
                     WebPIDecoder *decoder)
 {