Change hasThis to check ActRec::m_this & 1 again

It was checking & 3, and I couldn't figure out why.  It looks
like it was introduced probably accidentally by D498715.

hphp/runtime/ext/ext_closure.cpp

@@ -26,7 +26,7 @@ c_Closure::c_Closure(Class* cb) : ExtObjectData(cb),
   m_thisOrClass(nullptr), m_func(nullptr) {}
 c_Closure::~c_Closure() {
   // same as ar->hasThis()
-  if (m_thisOrClass && !(intptr_t(m_thisOrClass) & 3LL)) {
+  if (m_thisOrClass && !(intptr_t(m_thisOrClass) & 1LL)) {
     m_thisOrClass->decRefCount();
   }
 }

hphp/runtime/vm/bytecode.h

@@ -337,7 +337,7 @@ struct ActRec {
 
 #define UNION_FIELD_ACCESSORS2(name1, type1, field1, name2, type2, field2) \
   inline bool has##name1() const { \
-    return field1 && !(intptr_t(field1) & 3LL); \
+    return field1 && !(intptr_t(field1) & 1LL); \
   } \
   inline bool has##name2() const { \
     return bool(intptr_t(field2) & 1LL); \