Spotted by Vitaliy Margolen.

This prevents schan_resize_current_buffer() from thinking there's a buffer.

Cards that have 12 or more combined samplers can trigger a fixme if they have
the same amount of vertex samplers, even though it's plenty enough.

Requires changes in the way document locking is implemented and tested.

ole32: Explicitly add the three ULONGs from the METAFILEPICT struct to allow for padding in the 64-bit version.