Bring back positive version of default-switch.p4 test

testdata/p4_16_errors_outputs/default-last-switch.p4-stderr

@@ -0,0 +1,9 @@
+default-last-switch.p4(11): [--Werror=invalid] error: switch label b follows 'default' label, which is not allowed.
+        switch (t.apply().action_run) {
+        ^^^^^^
+default-last-switch.p4(13)
+            b: { return; }
+            ^
+default-last-switch.p4(12)
+            default:
+            ^^^^^^^

testdata/p4_16_samples/default-switch.p4

@@ -0,0 +1,16 @@
+control ctrl() {
+    action a() {}
+    action b() {}
+
+    table t {
+        actions = { a; b; }
+        default_action = a;
+    }
+
+    apply {
+        switch (t.apply().action_run) {
+            b:
+            default: { return; }
+        }
+    }
+}

testdata/p4_16_samples_outputs/default-switch-first.p4

@@ -0,0 +1,22 @@
+control ctrl() {
+    action a() {
+    }
+    action b() {
+    }
+    table t {
+        actions = {
+            a();
+            b();
+        }
+        default_action = a();
+    }
+    apply {
+        switch (t.apply().action_run) {
+            b: 
+            default: {
+                return;
+            }
+        }
+    }
+}
+

testdata/p4_16_samples_outputs/default-switch.p4

@@ -0,0 +1,22 @@
+control ctrl() {
+    action a() {
+    }
+    action b() {
+    }
+    table t {
+        actions = {
+            a;
+            b;
+        }
+        default_action = a;
+    }
+    apply {
+        switch (t.apply().action_run) {
+            b: 
+            default: {
+                return;
+            }
+        }
+    }
+}
+

testdata/p4_16_samples_outputs/default-switch.p4-stderr

@@ -0,0 +1,4 @@
+default-switch.p4(1): [--Wwarn=unused] warning: Control ctrl is not used; removing
+control ctrl() {
+        ^^^^
+[--Wwarn=missing] warning: Program does not contain a `main' module