wined3d: Properly check if the swapchain format is WINED3DFMT_P8_UINT in primary_render_target_is_p8().

The surface needs to be part of a swapchain to be flipped, but that doesn't
have much to do with WINED3DUSAGE_RENDERTARGET. We can just remove the check
here, because ddraw_surface7_Flip() already has the correct check.

r500 does not support anything but AMD's extension depth texture formats
on Windows 7. Plain surfaces work OK with the builtin formats.

wined3d: Replace surface_modify_location(surface, location, FALSE) calls with surface_invalidate_location().

wined3d: Get rid of the special SFLAG_INTEXTURE / SFLAG_INSRGBTEX code in surface_modify_location().

It turns out this is already safe for all callers.

It's fairly common in Mac keyboard layouts that, if you type a dead key twice,
the second key press will both produce a non-dead character and also
perpetuate the dead-key state.  For example, with the U.S. layout, Option-E,
E will produce "é" and Option-E, Option-E, E will produce "´é".  Windows
keyboard layouts don't tend to do this.  The second key press produces the
non-dead character and clears the dead-key state.