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.

They crash the GPU driver of my r200 WinXP laptop, causing anything from
a BSOD to a frozen or black screen and sometimes incorrectly set
resolutions.

wined3d: Only invalidate STATE_INDEXBUFFER for the current context in buffer_create_buffer_object().

wined3d: Rewrite surface_modify_location() on top of surface_validate_location() and surface_invalidate_location().

Otherwise invoking winegcc on any platform where our first guess at
the link options fails results in a lot of confusing error messages.

This stops the tested gcc command from issuing a warning on Solaris.