This are internal helper functions; the API functions that use them
already use LONG.

user32: Use a simplified sequence to destroy windows at thread exit, since we don't want to send messages.

winapi_extract: --spec-files has been broken for a long time and does not seem to be useful so remove it.

Using GL_NV_vertex_program2_option so far. If we're really desparate we can
handle some cases without the extension by using a custom varying and texkill
in the fragment program.

The view matrix that was set at the time the clipplane was applied is
hardcoded into the clipplane. With vertex shaders clip planes ignore
the view matrix in d3d. We implement that, but this also means that
the clip planes potentially change when we switch between vs and fixed
func.

This gives a small performance improvement. Don't enable NVfp for it though,
because the NVfp penalty is bigger than the gain from this patch. But if NVfp
is enabled anyway, make use of it.

The ARB "LRP" instruction is a fragment program only instruction. It is
however valid in vs_2_0+ vertex shaders, so we have to emulate it.