Global C++ constructors and destructors work again. Fixes #42.

examples/test-ctors.cpp

@@ -0,0 +1,29 @@
+#include <stdio.h>
+
+#ifdef __A
+struct A {
+  int i;
+  A(int _i) { i = _i; puts("ctor A"); }
+  ~A() { puts("dtor A"); }
+};
+
+A a(10);
+#endif
+
+#ifdef __B
+struct B {
+  int i;
+  B(int _i) { i = _i; puts("ctor B"); }
+  ~B() { puts("dtor B"); }
+};
+
+B b(20);
+#endif
+
+#if !defined(__A) && !defined(__B)
+int main()
+{
+  puts("hello world!");
+  return 0;
+}
+#endif