nqp::bitor_s and nqp::bitxor_s shouldn't truncate.
nqp::bitor_s and nqp::bitxor_s shouldn't truncate.

Fixes some failing bitwise operator tets for Rakudo JVM.

cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp