rpcrt4: Fix NdrConformantVaryingStructUnmarshall to use buffer memory if applicable and to reuse memory for embedded pointers.

rpcrt4: Factor out string validation from NDR unmarshalling functions into a separate function, validate_string_data.

Do so by calculating the alignment of members when iterating through
the structures and adding it onto the buffer and memory offsets.

Only call type_memsize once elsewhere in the embedded pointer
processing functions since the return value will be the same from the
second call.

Currently we only check if ARB_HALF_FLOAT_PIXEL is supported. This is
not enough, we need ARB_TEXTURE_FLOAT as well. This fixes some errors
when running the d3d9 visual test with Mesa swrast.

Both WINED3DUSAGE_OVERLAY and WINED3DUSAGE_QUERY_SRGBBLEND were using
the same value. All usage flags except for OVERLAY are directly mapped
to d3d9, so give OVERLAY its own value.

wined3d: Update the Nvidia driver version to 173.41 and also put it in the right format e.g. 7.15.11.7341 instead of 7.15.10.17341.