* [IERNONCE] Implement the registry management code.
* [EXPLORER] handle RunOnceEx by invoking RunOnceEx in iernonce.dll
* [IERNONCE] Display a dialog to show progress, and execute entries.
* [IERNONCE] Add `InitCallback` function
There is no need to compile our DLLs as shared libraries since we are
managing symbols exports and imports through spec files.
On my system, this reduces the configure-time by a factor of two.