9pfs: Stop including gstrfuncs.h

gstrfuncs.h is not intended to be included directly.
In fact this only works because glib.h is already included by osdep.h.
Just remove the include.

Signed-off-by: Peter Foley <pefoley@google.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Link: https://lore.kernel.org/qemu-devel/20250905-9p-v2-1-2ad31999684d@google.com
Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>

hw/9pfs/9p-util-generic.c

@@ -2,7 +2,6 @@
 
 #include "qemu/osdep.h"
 #include "9p-util.h"
-#include <glib/gstrfuncs.h>
 
 char *qemu_open_flags_tostr(int flags)
 {