add a test which ensures that bit shift right is an arithmetic shift, not logical shift.

test/dat.h

@@ -2,10 +2,12 @@
 
 #include "../src/util/conf.h"
 #include "../src/util/types.h"
+#include "t_arith.h"
 #include "t_conf.h"
 #include "test.h"
 
 testdat tests[] = {
+	{"ensure SAR",  test_sar,                NULL									    },
 	{"k=v",         test_procbuf,            &(struct test_procbuf){"key=val", "key", "val", 0}                              },
 	{"sometxt",     test_procbuf,            &(struct test_procbuf){"sometxt", "sometxt", "", CONF_ESYNTAX}                  },
 	{"comment",     test_procbuf,            &(struct test_procbuf){"# comment", "", "", CONF_ENODAT}                        },

test/t_arith.h

@@ -0,0 +1,8 @@
+#pragma once
+
+#include "test.h"
+
+int test_sar(void *dat) {
+	(void)dat;
+	return assert_true(-3 >> 5 == -1);
+}