linux: use sys/stat.h instead of linux/stat.h

glibc includes linux/stat.h for statx, but musl defines its own statx
struct and associated constants, which does not include STATX_MNT_ID
yet. Thus, including linux/stat.h directly should be avoided for
maximum libc compatibility.

Tested on:
  - glibc: x86_64, i686, aarch64, armv7l, armv6l
  - musl: x86_64, aarch64, armv7l, armv6l

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Tested-By: Achill Gilgenast <achill@achill.org>

Closes #17675
(cherry picked from commit ccf5a8a6fc)

Signed-off-by: classabbyamp <dev@placeviolette.net>
Signed-off-by: Alexander Moch <mail@alexmoch.com>
Co-authored-by: classabbyamp <5366828+classabbyamp@users.noreply.github.com>

include/os/linux/spl/sys/stat.h

@@ -25,6 +25,6 @@
 #ifndef _SPL_STAT_H
 #define	_SPL_STAT_H
 
-#include <linux/stat.h>
+#include <sys/stat.h>
 
 #endif /* SPL_STAT_H */