Use new bitwise Int# primops in Data.Bits (re #8791)

The new primops (see also #7689) allow to optimize
`instance Bits Int` by allowing to operate directly on Int#
instead of having to convert to Word# and back to Int# again.

Authored-by: Chris Dueck <crdueck@uwaterloo.ca>
Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>