cursor: Consistently use g_memdup() for cursor data

Currently, red-parse-qxl.c uses g_malloc+memcpy to duplicate the cursor
data when it could use g_memdup() instead. red-stream-device.c does the
same thing but uses spice_memdup(). This commit makes use of g_memdup()
in both cases so that this memory is consistently allocated through
glib.

Signed-off-by: Christophe Fergeau <cfergeau@redhat.com>

server/red-parse-qxl.c

@@ -1450,8 +1450,7 @@ static bool red_get_cursor(RedMemSlotInfo *slots, int group_id,
     if (free_data) {
         red->data = data;
     } else {
-        red->data = g_malloc(size);
-        memcpy(red->data, data, size);
+        red->data = g_memdup(data, size);
     }
     return true;
 }

server/red-stream-device.c

@@ -344,7 +344,7 @@ stream_msg_cursor_set_to_cursor_cmd(const StreamMsgCursorSet *msg, size_t msg_si
         return NULL;
     }
     cursor->data_size = size_required;
-    cursor->data = spice_memdup(msg->data, size_required);
+    cursor->data = g_memdup(msg->data, size_required);
     return cmd;
 }