ntdll: When tracking allocated blocks, RtlDestroyHeap must notify that all the blocks are being freed.

Fixes a regression in installing the DirectX 9 runtime.
Based on code from cabinet.dll's fdi.c, thus the healthy dose of
attributions.  Unfortunately there's no public API that'll get this
info for me (that I know of.)

This is an ATI specific format designed for compressed normal maps,
and quite a few games check for its existence. While it is an
ATI-specific "extension" in d3d9, it is a core part of
D3D10(DXGI_FORMAT_BC5), and supported on Geforce 8 cards.