src/cloner: use btrfs/ioctl.h header if present

Check for the btrfsprogs-devel ioctl.h header at configure time. Use it
in src/cloner if present, otherwise fall back to using the copied clone
ioctl definitions.

Signed-off-by: David Disseldorp <ddiss@suse.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

configure.ac

@@ -30,6 +30,7 @@ AC_HEADER_STDC
     AC_CHECK_HEADERS([	sys/fs/xfs_fsops.h	\
 			sys/fs/xfs_itable.h	\
 			xfs/platform_defs.h	\
+			btrfs/ioctl.h		\
     ])
 
 AC_PACKAGE_NEED_UUIDCOMPARE

src/cloner.c

@@ -30,6 +30,9 @@
 #include <stdio.h>
 #include <string.h>
 #include <errno.h>
+#ifdef HAVE_BTRFS_IOCTL_H
+#include <btrfs/ioctl.h>
+#else
 
 struct btrfs_ioctl_clone_range_args {
 	int64_t src_fd;
@@ -42,6 +45,7 @@ struct btrfs_ioctl_clone_range_args {
 #define BTRFS_IOC_CLONE       _IOW(BTRFS_IOCTL_MAGIC, 9, int)
 #define BTRFS_IOC_CLONE_RANGE _IOW(BTRFS_IOCTL_MAGIC, 13, \
 				   struct btrfs_ioctl_clone_range_args)
+#endif
 
 static void
 usage(char *name, const char *msg)