[PATCH 6.1 5.15 5.10 5.4 4.19 4.14] selftests/memfd: Fix unknown type name build failure

[Hardik Garg <hargar@linux.microsoft.com>]

Partially backport v6.3 commit 11f75a01448f ("selftests/memfd: add
tests for MFD_NOEXEC_SEAL MFD_EXEC") to fix an unknown type name 
build error.
In some systems, the __u64 typedef is not present due to differences
in system headers, causing compilation errors like this one:

fuse_test.c:64:8: error: unknown type name '__u64'
   64 | static __u64 mfd_assert_get_seals(int fd)

This header includes the  __u64 typedef which increases the
likelihood of successful compilation on a wider variety of systems.

Signed-off-by: Hardik Garg <hargar@linux.microsoft.com>
---
 tools/testing/selftests/memfd/fuse_test.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/testing/selftests/memfd/fuse_test.c b/tools/testing/selftests/memfd/fuse_test.c
index be675002f918..93798c8c5d54 100644
--- a/tools/testing/selftests/memfd/fuse_test.c
+++ b/tools/testing/selftests/memfd/fuse_test.c
@@ -22,6 +22,7 @@
 #include <linux/falloc.h>
 #include <fcntl.h>
 #include <linux/memfd.h>
+#include <linux/types.h>
 #include <sched.h>
 #include <stdio.h>
 #include <stdlib.h>
-- 
2.25.1