interp: keep reverted package initializers in order

Previously, a package initializer that could not be reverted correctly
would be called at runtime. But the initializer would be called in the
wrong order: after later packages are initialized.

This commit fixes this oversight and adds a test to verify the new
behavior.

interp/interp_test.go

@@ -17,6 +17,7 @@ func TestInterp(t *testing.T) {
 		"slice-copy",
 		"consteval",
 		"interface",
+		"revert",
 	} {
 		name := name // make tc local to this closure
 		t.Run(name, func(t *testing.T) {