After drawing from a vertex array we should disable them, to prevent
the next draw calls from potentially reading past their ends. This
also moves the disabling of vertex attrib arrays (for shaders) into
its own function.

riched20: Make EM_LINELENGTH work correctly for non-final paragraphs containing exactly one screen line.

Otherwise, an IStream_SetSize call followed by an IStream_Read call 
could fail with STG_E_DOCFILECORRUPT.

It has a tendency to trigger X11 bugs, and it's not really useful anyway.

This lets ddraw dlls built on a machine with OpenGL present run on other 
machines that may not have the OpenGL libraries installed.