tests: extend test coverage of getresuid32 syscall

* tests/getresuid32.c: New file.
* tests/getresuid32.test: New test.
* tests/.gitignore: Add getresuid32.
* tests/Makefile.am (check_PROGRAMS): Likewise.
(DECODER_TESTS): Add getresuid32.test.
diff --git a/tests/Makefile.am b/tests/Makefile.am
index a29e71a..aa1d813 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -115,6 +115,7 @@
 	getgroups32 \
 	getrandom \
 	getresuid \
+	getresuid32 \
 	getrusage \
 	getxxid \
 	inet-cmsg \
@@ -352,6 +353,7 @@
 	getgroups32.test \
 	getrandom.test \
 	getresuid.test \
+	getresuid32.test \
 	getrusage.test \
 	getxxid.test \
 	inet-cmsg.test \