qemu-config.h: Include headers it needs

Include:
- <stdio.h> for FILE
- qemu-option.h for QemuOptsList

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: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>

qemu-config.h

@@ -1,6 +1,8 @@
 #ifndef QEMU_CONFIG_H
 #define QEMU_CONFIG_H
 
+#include <stdio.h>
+#include "qemu-option.h"
 #include "error.h"
 
 extern QemuOptsList qemu_fsdev_opts;