A jump that ends a basic block or otherwise falls back to CC_OP_DYNAMIC
will always have to call gen_op_set_cc_op.  However, not all jumps end
a basic block, so introduce a variant that does not do this.

This was partially undone earlier (i386: drop cc_op argument of gen_jcc1),
redo it now also to prepare for the introduction of src2.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NRichard Henderson <rth@twiddle.net>