d: Merge dmd, druntime 6884b433d2, phobos 48d581a1f

D front-end changes:

	- It's now deprecated to declare `auto ref' parameters without
	  putting those two keywords next to each other.
        - An error is now given for case fallthough for multivalued
	  cases.
        - An error is now given for constructors with field destructors
	  with stricter attributes.
        - An error is now issued for `in'/`out' contracts of `nothrow'
	  functions that may throw.
	- `auto ref' can now be applied to local, static, extern, and
	  global variables.

D runtime changes:

        - Import latest fixes from druntime v2.110.0-beta.1.

Phobos changes:

        - Import latest fixes from phobos v2.110.0-beta.1.

gcc/d/ChangeLog:

	* dmd/MERGE: Merge upstream dmd 6884b433d2.
	* d-builtins.cc (build_frontend_type): Update for new front-end
	interface.
	(d_build_builtins_module): Likewise.
	(matches_builtin_type): Likewise.
	(covariant_with_builtin_type_p): Likewise.
	* d-codegen.cc (lower_struct_comparison): Likewise.
	(call_side_effect_free_p): Likewise.
	* d-compiler.cc (Compiler::paintAsType): Likewise.
	* d-convert.cc (convert_expr): Likewise.
	(convert_for_assignment): Likewise.
	* d-target.cc (Target::isVectorTypeSupported): Likewise.
	(Target::isVectorOpSupported): Likewise.
	(Target::isReturnOnStack): Likewise.
	* decl.cc (get_symbol_decl): Likewise.
	* expr.cc (build_return_dtor): Likewise.
	* imports.cc (class ImportVisitor): Likewise.
	* toir.cc (class IRVisitor): Likewise.
	* types.cc (class TypeVisitor): Likewise.

libphobos/ChangeLog:

	* libdruntime/MERGE: Merge upstream druntime 6884b433d2.
	* src/MERGE: Merge upstream phobos 48d581a1f.