d: Merge upstream dmd 3982604c5, druntime bc58b1e9, phobos 12329adb6.

D front-end changes:

    - Import dmd mainline development.
    - Split off enum EXP from enum TOK.
    - Integer promotions now follow C integral promotions by default.
    - Implements __traits(initSymbol).
    - Lowering of array construction has been moved to the dmd
      front-end.
    - Fix segfault in dmd.lexer from unaligned read (PR103529).

Druntime changes:

    - Import druntime mainline development.
    - Define SIG_BLOCK for Solaris (PR103528).

Phobos changes:

    - Import phobos mainline development.

gcc/d/ChangeLog:

	PR d/103529
	* dmd/MERGE: Merge upstream dmd 3982604c5.
	* Make-lang.in (D_FRONTEND_OBJS): Add d/root-optional.o.
	* d-attribs.cc (build_attributes): Update for new front-end interface.
	* d-codegen.cc (d_build_call): Likewise.
	* d-compiler.cc (Compiler::paintAsType): Likewise.
	* d-lang.cc (d_handle_option): Remove OPT_fpreview_intpromote, add
	handling of OPT_frevert_intpromote.
	* d-port.cc (Port::valcpy): Assert buffer is aligned.
	* d-target.cc (Target::isVectorOpSupported): Update for new front-end
	interface.
	* decl.cc (layout_class_initializer): Likewise.
	* expr.cc (lvalue_p): Likewise.
	(binop_assignment): Likewise.
	(ExprVisitor::visit): Likewise.
	(ExprVisitor::visit (AssignExp *)): Remove generation of _d_arrayctor
	and _d_arraysetctor library helpers.
	(ExprVisitor::visit (VarExp *)): Support __traits(initSymbol).
	* intrinsics.cc (expand_intrinsic_rotate): Update for new front-end
	interface.
	* lang.opt (fpreview=intpromote): Remove.
	(frevert=intpromote): New.
	* runtime.def (ARRAYCTOR): Remove.
	(ARRAYSETCTOR): Remove.
	* toir.cc (IRVisitor::visit): Update for new front-end interface.
	* types.cc (layout_aggregate_members): Likewise.
	* dmd/root/optional.d: New file.
	* dmd/root/optional.h: New file.

libphobos/ChangeLog:

	PR d/103528
	* libdruntime/MERGE: Merge upstream druntime bc58b1e9.
	* libdruntime/Makefile.am (DRUNTIME_DSOURCES_LINUX): Remove
	core/sys/linux/syscalls.d.
	* libdruntime/Makefile.in: Regenerate.
	* src/MERGE: Merge upstream phobos 12329adb6.
	* testsuite/libphobos.config/config.exp: Add test22523.
	* libdruntime/core/sys/linux/syscalls.d: Removed.
	* testsuite/libphobos.config/test22523.d: New test.