tests: check decoding of chown32 syscall

* tests/chown32.c: New file.
* tests/chown32.test: New test.
* tests/.gitignore: Add chown32.
* tests/Makefile.am (check_PROGRAMS): Likewise.
(DECODER_TESTS): Add chown32.test.
diff --git a/tests/.gitignore b/tests/.gitignore
index ad27043..49f20c6 100644
--- a/tests/.gitignore
+++ b/tests/.gitignore
@@ -17,6 +17,7 @@
 caps
 chmod
 chown
+chown32
 chroot
 clock_nanosleep
 clock_xettime