[evolution-ews] Fix "assignment from incompatible pointer type" warning

[Fabiano Fidêncio <ffidencio src gnome org>]

commit 8ae531166669a86adfaf97dad5fcd20f3a522d8d
Author: Fabiano Fidêncio <fidencio redhat com>
Date:   Tue Nov 5 12:05:11 2013 +0100

    Fix "assignment from incompatible pointer type" warning

 src/camel/camel-ews-folder.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/src/camel/camel-ews-folder.c b/src/camel/camel-ews-folder.c
index 7912eca..ecda948 100644
--- a/src/camel/camel-ews-folder.c
+++ b/src/camel/camel-ews-folder.c
@@ -150,8 +150,8 @@ ews_data_cache_get (CamelDataCache *cdc,
        GIOStream *base_stream;
 
        g_checksum_update (sha, (guchar *) key, strlen (key));
-       base_stream = camel_data_cache_get (
-               cdc, path, g_checksum_get_string (sha), error);
+       base_stream = G_IO_STREAM (camel_data_cache_get (
+               cdc, path, g_checksum_get_string (sha), error));
        if (base_stream != NULL) {
                stream = camel_stream_new (base_stream);
                g_object_unref (base_stream);