Fix vma_adjust adjust_next wrapping: Rajesh V.  pointed out that if end were
2GB or more beyond next->vm_start (on 32-bit), then next->vm_pgoff would have
been negatively adjusted.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Rajesh Venkatasubramanian <vrajesh@umich.edu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>