tests: extend test coverage of setresuid syscall

* tests/setresugid.c: New file.
* tests/setresuid.c: New file.
* tests/setresuid.test: New test.
* tests/.gitignore: Add setresuid.
* tests/Makefile.am (check_PROGRAMS): Likewise.
(DECODER_TESTS): Add setresuid.test.
(EXTRA_DIST): Add setresugid.c.
diff --git a/tests/setresuid.test b/tests/setresuid.test
new file mode 100755
index 0000000..f1219e0
--- /dev/null
+++ b/tests/setresuid.test
@@ -0,0 +1,6 @@
+#!/bin/sh
+
+# Check setresuid syscall decoding.
+
+. "${srcdir=.}/init.sh"
+run_strace_match_diff -a19