Fixed handling of const objects in Callback class

Before, the following results in a compilation error:

    const struct Object *obj;
    void obj_doit(const Object *obj);

    Callback<void()> cb(obj, obj_doit);

This is especially noticable when migrating from the old Thread
constructor, which previously _required_ const.

Short term fix for all cv qualifiers through a C cast:
void *_obj = (void*)obj;

Author: geky

hal/api/Callback.h

@@ -80,7 +80,7 @@ class Callback<R(A0, A1, A2, A3, A4)> {
      */
     template <typename T>
     void attach(T *obj, R (*func)(T*, A0, A1, A2, A3, A4)) {
-        _obj = static_cast<void*>(obj);
+        _obj = (void*)obj;
         memcpy(&_func, &func, sizeof func);
         _thunk = &Callback::_boundthunk<T>;
     }
@@ -221,7 +221,7 @@ class Callback<R(A0, A1, A2, A3)> {
      */
     template <typename T>
     void attach(T *obj, R (*func)(T*, A0, A1, A2, A3)) {
-        _obj = static_cast<void*>(obj);
+        _obj = (void*)obj;
         memcpy(&_func, &func, sizeof func);
         _thunk = &Callback::_boundthunk<T>;
     }
@@ -362,7 +362,7 @@ class Callback<R(A0, A1, A2)> {
      */
     template <typename T>
     void attach(T *obj, R (*func)(T*, A0, A1, A2)) {
-        _obj = static_cast<void*>(obj);
+        _obj = (void*)obj;
         memcpy(&_func, &func, sizeof func);
         _thunk = &Callback::_boundthunk<T>;
     }
@@ -503,7 +503,7 @@ class Callback<R(A0, A1)> {
      */
     template <typename T>
     void attach(T *obj, R (*func)(T*, A0, A1)) {
-        _obj = static_cast<void*>(obj);
+        _obj = (void*)obj;
         memcpy(&_func, &func, sizeof func);
         _thunk = &Callback::_boundthunk<T>;
     }
@@ -644,7 +644,7 @@ class Callback<R(A0)> {
      */
     template <typename T>
     void attach(T *obj, R (*func)(T*, A0)) {
-        _obj = static_cast<void*>(obj);
+        _obj = (void*)obj;
         memcpy(&_func, &func, sizeof func);
         _thunk = &Callback::_boundthunk<T>;
     }
@@ -785,7 +785,7 @@ class Callback<R()> {
      */
     template <typename T>
     void attach(T *obj, R (*func)(T*)) {
-        _obj = static_cast<void*>(obj);
+        _obj = (void*)obj;
         memcpy(&_func, &func, sizeof func);
         _thunk = &Callback::_boundthunk<T>;
     }