MINOR: tests: First regression testing file.

Add a makefile target 'reg-tests' to run all regression testing file
found in 'reg-tests' directory.
Add reg-tests/lua/h00000.vtc first regression testing file for a LUA
fixed by f874a83 commit.
diff --git a/reg-tests/lua/h00000.lua b/reg-tests/lua/h00000.lua
new file mode 100644
index 0000000..d2401fa
--- /dev/null
+++ b/reg-tests/lua/h00000.lua
@@ -0,0 +1,3 @@
+core.register_action("foo", { "http-req" }, function(txn)
+	txn.sc:ipmask(txn.f:src(), 24, 112)
+end)