rpcrt4: Replace sizeofs with FIELD_OFFSET in RPCRT4_BuildBindNackHeader to avoid relying on ANYSIZE_ARRAY being 1.

Not all cards support dynamic usage textures, and we don't actually need it.

Fixes Valgrind errors in various tests using RPC.

The parameter is a pointer to an array, so don't access it like it is
an array of pointers.

Nvidia and Mesa ignore GLX_RENDER_TYPE when it is set to an invalid
value like 0 but AMD for instance doesn't, which is legal.

The term "property" is misleading (ole32 has an unrelated feature
called a "property set storage"), and I haven't seen it used anywhere
outside the Wine code. The term "directory entry" matches the MS
documentation and more accurately describes their use in the file.

According to the MS spec, the types in compound storage files are simply
STGTY values, with an extra value named STGTY_ROOT for the root storage.

winex11: Implement AlphaBlend mode for the case where SourceConstantAlpha is combined with source alpha.