oleaut32: Re-arrange the position of functions and vtables in olefont.c to avoid forward-declarations.

The tests show that there is a global cache that keeps references to 
HFONTs that is released when all IFont objects are released.
(Based on a patch by Benjamin Arai.)

Volumetexture::Release checks for NULL pointers, so releasing a partially 
created texture works.

kernel32: Don't run the CreateRemoteThread tests if the child process isn't mapped at the same address as the parent process.