[PATCH] fix __div64_32 to do division properly

[PATCH] fix __div64_32 to do division properly

This fixes the generic __div64_32() to correctly handle divisions by
large 32-bit values (as used by nanosleep() and friends, for example).

It's a simple bit-at-a-time implementation with a reduction of the high
32-bits handled manually.  Architectures that can do 64/32-bit divisions
in hardware should implement their own more efficient versions.