wined3d: Remove the swapchain parameter from fb_copy_to_texture_hwstretch in order to unify all blit calls.

advapi32: Don't use the static Unicode buffer for value names since they can be larger than MAX_PATH.

Assume the function pointers retrieved by alGetProcAddress are context
independent. This is not likely to change in any implementation we
care about any time soon.

This ensures there's no multilevel indirection in the state table.