tools headers uapi: Sync linux/fcntl.h with the kernel sources

To get the changes in:

  96b2b07 ("exportfs: allow exporting non-decodeable file handles to userspace")

That don't add anything that is handled by existing hard coded tables or
table generation scripts.

This silences this perf build warning:

  Warning: Kernel ABI header differences:
    diff -u tools/include/uapi/linux/fcntl.h include/uapi/linux/fcntl.h

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/lkml/ZK11P5AwRBUxxutI@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Author: acmel

tools/include/uapi/linux/fcntl.h

@@ -112,4 +112,9 @@
 
 #define AT_RECURSIVE		0x8000	/* Apply to the entire subtree */
 
+/* Flags for name_to_handle_at(2). We reuse AT_ flag space to save bits... */
+#define AT_HANDLE_FID		AT_REMOVEDIR	/* file handle is needed to
+					compare object identity and may not
+					be usable to open_by_handle_at(2) */
+
 #endif /* _UAPI_LINUX_FCNTL_H */