Fix PR 109919: ICE in emit_move_insn with some bit tests

Fix PR 109919: ICE in emit_move_insn with some bit tests

The problem is I used expand_expr with the target but
we don't want to use the target here as it is the wrong
mode for the original expression. The testcase would ICE
deap down while trying to do a move to use the target.
Anyways just calling expand_expr with NULL_EXPR fixes
the issue.

Committed as obvious after a bootstrap/test on x86_64-linux-gnu.

	PR middle-end/109919

gcc/ChangeLog:

	* expr.cc (expand_single_bit_test): Don't use the
	target for expand_expr.

gcc/testsuite/ChangeLog:

	* gcc.c-torture/compile/pr109919-1.c: New test.