linux-user: include linux/fs.h

defines FIGETBSZ FIBMAP, allowing the respective ioctl's to
be implemented.

From: Martin Mohring <martin.mohring@opensuse.org>
Signed-off-by: Riku Voipio <riku.voipio@iki.fi>
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 674942c..0c7ce51 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -77,6 +77,7 @@
 #include <linux/soundcard.h>
 #include <linux/kd.h>
 #include <linux/mtio.h>
+#include <linux/fs.h>
 #include "linux_loop.h"
 
 #include "qemu.h"