selftest for default_file_splice_read() infoleak

bug fixed in commit b9dc6f65bc5e ("fix a fencepost error in pipe_advance()")

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 71b0589..0e72f1d 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -24,6 +24,7 @@
 TARGETS += seccomp
 TARGETS += sigaltstack
 TARGETS += size
+TARGETS += splice
 TARGETS += static_keys
 TARGETS += sync
 TARGETS += sysctl