Handle const_int in expand_single_bit_test

Handle const_int in expand_single_bit_test

After expanding directly to rtl instead of
creating a tree, we could end up with
a const_int which is not ready to be handled
by extract_bit_field.
So need to the constant folding here instead.

OK? bootstrapped and tested on x86_64-linux-gnu with no regressions.

	PR middle-end/110117

gcc/ChangeLog:

	* expr.cc (expand_single_bit_test): Handle
	const_int from expand_expr.

gcc/testsuite/ChangeLog:

	* gcc.dg/pr110117-1.c: New test.
	* gcc.dg/pr110117-2.c: New test.