[PATCH] Pass vma argument to copy_user_highpage().
To allow a more effective copy_user_highpage() on certain architectures,
a vma argument is added to the function and cow_user_page() allowing
the implementation of these functions to check for the VM_EXEC bit.
The main part of this patch was originally written by Ralf Baechle;
Atushi Nemoto did the the debugging.