libfuse: don't put HAVE_STATX in a public header

fuse.h and fuse_lowlevel.h are public headers, don't expose internal
build system config variables to downstream clients.  This can also lead
to function pointer ordering issues if (say) libfuse gets built with
HAVE_STATX but the client program doesn't define a HAVE_STATX.

Get rid of the conditionals in the public header files to fix this.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
diff --git a/example/memfs_ll.cc b/example/memfs_ll.cc
index edda34b..7055a43 100644
--- a/example/memfs_ll.cc
+++ b/example/memfs_ll.cc
@@ -6,7 +6,7 @@
   See the file GPL2.txt.
 */
 
-#define FUSE_USE_VERSION 317
+#define FUSE_USE_VERSION FUSE_MAKE_VERSION(3, 18)
 
 #include <algorithm>
 #include <stdio.h>
diff --git a/example/passthrough.c b/example/passthrough.c
index fdaa19e..1f09c2d 100644
--- a/example/passthrough.c
+++ b/example/passthrough.c
@@ -23,7 +23,7 @@
  */
 
 
-#define FUSE_USE_VERSION 31
+#define FUSE_USE_VERSION FUSE_MAKE_VERSION(3, 18)
 
 #define _GNU_SOURCE
 
diff --git a/example/passthrough_fh.c b/example/passthrough_fh.c
index 0d4fb5b..6403fbb 100644
--- a/example/passthrough_fh.c
+++ b/example/passthrough_fh.c
@@ -23,7 +23,7 @@
  * \include passthrough_fh.c
  */
 
-#define FUSE_USE_VERSION 31
+#define FUSE_USE_VERSION FUSE_MAKE_VERSION(3, 18)
 
 #define _GNU_SOURCE
 
diff --git a/example/passthrough_ll.c b/example/passthrough_ll.c
index 5ca6efa..8a5ac2e 100644
--- a/example/passthrough_ll.c
+++ b/example/passthrough_ll.c
@@ -35,7 +35,7 @@
  */
 
 #define _GNU_SOURCE
-#define FUSE_USE_VERSION FUSE_MAKE_VERSION(3, 12)
+#define FUSE_USE_VERSION FUSE_MAKE_VERSION(3, 18)
 
 #include <fuse_lowlevel.h>
 #include <unistd.h>
diff --git a/include/fuse.h b/include/fuse.h
index 06feacb..2091026 100644
--- a/include/fuse.h
+++ b/include/fuse.h
@@ -854,7 +854,6 @@
 	 */
 	off_t (*lseek) (const char *, off_t off, int whence, struct fuse_file_info *);
 
-#ifdef HAVE_STATX
 	/**
 	 * Get extended file attributes.
 	 *
@@ -865,7 +864,6 @@
 	 */
 	int (*statx)(const char *path, int flags, int mask, struct statx *stxbuf,
 		     struct fuse_file_info *fi);
-#endif
 };
 
 /** Extra context that may be needed by some filesystems
diff --git a/include/fuse_lowlevel.h b/include/fuse_lowlevel.h
index dc4ec07..a6cce01 100644
--- a/include/fuse_lowlevel.h
+++ b/include/fuse_lowlevel.h
@@ -1327,7 +1327,6 @@
 	void (*tmpfile) (fuse_req_t req, fuse_ino_t parent,
 			mode_t mode, struct fuse_file_info *fi);
 
-#ifdef HAVE_STATX
 	/**
 	 * Get extended file attributes.
 	 *
@@ -1343,7 +1342,6 @@
 	 */
 	void (*statx)(fuse_req_t req, fuse_ino_t ino, int flags, int mask,
 		      struct fuse_file_info *fi);
-#endif
 };
 
 /**