tests: check decoding of lchown32 syscall

* tests/lchown32.c: New file.
* tests/lchown32.test: New test.
* tests/.gitignore: Add lchown32.
* tests/Makefile.am (check_PROGRAMS): Likewise.
(DECODER_TESTS): Add lchown32.test.
diff --git a/tests/.gitignore b/tests/.gitignore
index 1e138b0..99411f2 100644
--- a/tests/.gitignore
+++ b/tests/.gitignore
@@ -70,6 +70,7 @@
 ksysent
 ksysent.h
 lchown
+lchown32
 libtests.a
 linkat
 llseek