[libsoup] Silence Clang warning

[Patrick Griffis <pgriffis src gnome org>]

commit 5d12f5ca6702c157977f2aa9b5629dfdac83a6e6
Author: Patrick Griffis <pgriffis igalia com>
Date:   Wed Dec 16 15:33:16 2020 -0600

    Silence Clang warning

 libsoup/content-sniffer/soup-content-sniffer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/libsoup/content-sniffer/soup-content-sniffer.c b/libsoup/content-sniffer/soup-content-sniffer.c
index 51fe3ba8..d3bd6405 100644
--- a/libsoup/content-sniffer/soup-content-sniffer.c
+++ b/libsoup/content-sniffer/soup-content-sniffer.c
@@ -651,7 +651,7 @@ sniff_feed_or_html (SoupContentSniffer *sniffer, GBytes *buffer)
                goto text_html;
 
        /* Skip a leading UTF-8 BOM */
-       if (resource[0] == 0xEF && resource[1] == 0xBB && resource[2] == 0xBF)
+       if ((guchar)resource[0] == 0xEF && (guchar)resource[1] == 0xBB && (guchar)resource[2] == 0xBF)
                pos = 3;
 
  look_for_tag: