d: Merge upstream dmd 56f0a65c4.

d: Merge upstream dmd 56f0a65c4.

Updates the Target interface, removing static from all members, so all
field accesses and member function calls go through a single global
'target'.  Information relating to extern ABI are now in TargetC,
TargetCPP, and TargetObjC for each supported language respectively.

Reviewed-on: https://github.com/dlang/dmd/pull/11228

gcc/d/ChangeLog:

	* dmd/MERGE: Merge upstream dmd 56f0a65c4.
	* d-builtins.cc (build_frontend_type): Remove static.
	(d_build_builtins_module): Use target.va_listType() to get front-end
	type for va_list.
	(d_init_builtins): Move creation of va_list to Target::va_listType.
	* d-codegen.cc (build_interface_binfo): Use new target global.
	(build_vindex_ref): Likewise.
	(identity_compare_p): Likewise.
	* d-ctfloat.cc (CTFloat::parse): Likewise.
	* d-lang.cc (d_init): Likewise.
	* d-port.cc (Port::isFloat32LiteralOutOfRange): Likewise.
	(Port::isFloat64LiteralOutOfRange): Likewise.
	* d-target.cc (define_float_constants): Initialize constants through a
	reference, instead of setting globals.
	(Target::_init): Initialize new fields instead of setting globals.
	(Target::va_listType): Build front-end type from va_list_type_node.
	(Target::toCppMangle): Renamed to ...
	(TargetCPP::toMangle): ... this.
	(Target::cppTypeInfoMangle): Renamed to ...
	(TargetCPP::typeInfoMangle): ... this.
	(Target::cppTypeMangle): Renamed to ...
	(TargetCPP::typeMangle): this.
	(Target::cppParameterType): Renamed to ...
	(TargetCPP::parameterType): ... this.  Use target.va_listType() to get
	front-end type for va_list.
	(Target::cppFundamentalType): Renamed to ...
	(TargetCPP::fundamentalType): ... this.
	* d-tree.h (build_frontend_type): Declare.
	* decl.cc (base_vtable_offset): Use new target global.
	* typeinfo.cc (layout_classinfo_interfaces): Likewise.
	(layout_cpp_typeinfo): Likewise.
	* types.cc (valist_array_p): Use target.va_listType() to get front-end
	type for va_list.
	(layout_aggregate_type): Use new target global.