linux(4): Quiesce unrecognized ioctl warning for F2FS query

On Linux, sqlite probes for underlying F2FS filesystems that support
certain kinds of atomic update with this ioctl.  The expected result on
non-F2FS filesystem (i.e., all FreeBSD filesystems) is any error value.

Minimally implement the ioctl and avoid the warning message.

(This shows up in Linux Chrome, which embeds sqlite.)

Reviewed by:	emaste, trasz
Differential Revision:	https://reviews.freebsd.org/D27050

sys/compat/linux/linux_ioctl.c

@@ -3631,6 +3631,7 @@ linux_ioctl_fallback(struct thread *td, struct linux_ioctl_args *args)
 
 	switch (args->cmd & 0xffff) {
 	case LINUX_BTRFS_IOC_CLONE:
+	case LINUX_F2FS_IOC_GET_FEATURES:
 	case LINUX_FS_IOC_FIEMAP:
 		return (ENOTSUP);
 

sys/compat/linux/linux_ioctl.h

@@ -707,6 +707,11 @@
 #define LINUX_IOCTL_VIDEO2_MIN	LINUX_VIDIOC_QUERYCAP
 #define LINUX_IOCTL_VIDEO2_MAX	LINUX_VIDIOC_UNSUBSCRIBE_EVENT
 
+#define	LINUX_F2FS_IOC_GET_FEATURES		0xf50c /* 0x8004f50c */
+
+#define	LINUX_IOCTL_F2FS_MIN			0xf500
+#define	LINUX_IOCTL_F2FS_MAX	LINUX_F2FS_IOC_GET_FEATURES
+
 /*
  * Our libusb(8) calls emulated within linux(4).
  */