ui/vnc-palette.c: Include headers it needs

Include:
 - <glib.h> for g_malloc0()
 - <string.h> for memset()

Some of those headers were probably being included by accident because
some other headers were including qemu-common.h, but those headers
should eventually stop including qemu-common.h.
Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>
Signed-off-by: NAndreas Färber <afaerber@suse.de>

ui/vnc-palette.c

@@ -27,6 +27,8 @@
  */
 
 #include "vnc-palette.h"
+#include <glib.h>
+#include <string.h>
 
 static VncPaletteEntry *palette_find(const VncPalette *palette,
                                      uint32_t color, unsigned int hash)