[balsa/gmime3] Adapt to new g_mime_utils_header_decode_date() API

[Peter Bloomfield <peterb src gnome org>]

commit 55e638a7b8fa60aa2dff3ac8106a5ff7e7474686
Author: Albrecht Dreß <albrecht dress arcor de>
Date:   Sun Nov 24 13:01:45 2019 -0500

    Adapt to new g_mime_utils_header_decode_date() API
    
    modified:   libbalsa/imap/imap-handle.c

 libbalsa/imap/imap-handle.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)
---
diff --git a/libbalsa/imap/imap-handle.c b/libbalsa/imap/imap-handle.c
index 343b8eb17..b51e53f2d 100644
--- a/libbalsa/imap/imap-handle.c
+++ b/libbalsa/imap/imap-handle.c
@@ -3077,7 +3077,15 @@ ir_envelope(NetClientSioBuf *sio, ImapEnvelope *env)
 
   date = imap_get_nstring(sio);
   if(date) {
-    if(env) env->date = g_mime_utils_header_decode_date(date, NULL);
+    if (env != NULL) {
+      GDateTime *header_date;
+
+      header_date = g_mime_utils_header_decode_date(date);
+      if (header_date != NULL) {
+        env->date = (time_t) g_date_time_to_unix(header_date);
+        g_date_time_unref(header_date);
+      }
+    }
     g_free(date);
   }
   if( (c=sio_getc(sio)) != ' ') return IMR_PROTOCOL;