fglrx refuses to use PBOs on not mipmap complete textures. The texture code
already takes care of this, do the same in the test.

Nvidia doesn't offer it on geforce 7 and earlier cards, but some games need
it. This is surprising because the extension was made specifically for
compatibility purposes for older cards.

Checking for the doublebuffer flag can cause confusion if no VBO has
been allocated for the buffer. Checking for allocatedMemory is the
more direct approach.

This fixes a regression in EverQuest 2.

wined3d: Use shader_sm1_read_dst_param() and shader_sm1_read_src_param() in shader_get_registers_used().