patch 9.0.1963: Configure script may not detect xattr

Problem:  Configure script may not detect xattr correctly
Solution: include sys/xattr instead of attr/xattr,
          make Test_write_with_xattr_support() test
          xattr feature correctly

This also applies to the Smack security feature, so change the include
and configure script for it as well.

closes: #13229

Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: zeertzjq <zeertzjq@outlook.com>
diff --git a/src/os_unix.c b/src/os_unix.c
index 674dd96..50acd5a 100644
--- a/src/os_unix.c
+++ b/src/os_unix.c
@@ -36,12 +36,12 @@
 #endif
 
 #ifdef FEAT_XATTR
-# include <attr/xattr.h>
+# include <sys/xattr.h>
 # define XATTR_VAL_LEN 1024
 #endif
 
 #ifdef HAVE_SMACK
-# include <attr/xattr.h>
+# include <sys/xattr.h>
 # include <linux/xattr.h>
 # ifndef SMACK_LABEL_LEN
 #  define SMACK_LABEL_LEN 1024