These APIs deal with bitmaps representing contiguous
memory regions.  The idea is to set, free and find
a contiguous area.

For ease of implementation (as well as to conform
to the standard requirements), the bitmaps always
return n aligned n length regions.  The implementation
is also limited to BITS_PER_LONG contiguous regions.
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>