d: Fix ICE: in verify_gimple_in_seq on powerpc-darwin9 [PR112270]

This ICE was seen during stage2 on powerpc-darwin9 only.  There were
still some uses of GCC's boolean_type_node in the D front-end, which
caused a type mismatch to trigger as D bool size is fixed to 1 byte on
all targets.

So two new nodes have been introduced - d_bool_false_node and
d_bool_true_node - which have replaced all remaining uses of
boolean_false_node and boolean_true_node respectively.

	PR d/112270

gcc/d/ChangeLog:

	* d-builtins.cc (d_build_d_type_nodes): Initialize d_bool_false_node,
	d_bool_true_node.
	* d-codegen.cc (build_array_struct_comparison): Use d_bool_false_node
	instead of boolean_false_node.
	* d-convert.cc (d_truthvalue_conversion): Use d_bool_false_node and
	d_bool_true_node instead of boolean_false_node and boolean_true_node.
	* d-tree.h (enum d_tree_index): Add DTI_BOOL_FALSE and DTI_BOOL_TRUE.
	(d_bool_false_node): New macro.
	(d_bool_true_node): New macro.
	* modules.cc (build_dso_cdtor_fn): Use d_bool_false_node and
	d_bool_true_node instead of boolean_false_node and boolean_true_node.
	(register_moduleinfo): Use d_bool_type instead of boolean_type_node.

gcc/testsuite/ChangeLog:

	* gdc.dg/pr112270.d: New test.