d: Merge upstream dmd c11e1d1708, druntime e60bfd11bd, phobos 8729740e3

Synchronizing the compiler with the upstream release of v2.108.1.

D front-end changes:

        - Import dmd v2.108.1.
	- Add experimental support for language editions, enabled by
	  adding the UDA `@__edition_latest_do_not_use' before module
	  declarations.
	- [Next Edition] Aliasing a member of a type instance is now an
	  error.
	- Added `__ctfeWrite' to write messages from CTFE.
	- `-fdump-c++-spec' generates signatures for `extern(Windows)'
	  and `extern(System)' functions.
	- `foreach_reverse' on a delegate is now an error.
	- ImportC has improved Unicode support.

D runtime changes:

        - Mark unsafe unittest @trusted.

Phobos changes:

        - Mark unsafe functions @trusted.

gcc/d/ChangeLog:

	* Make-lang.in (D_FRONTEND_OBJS): Add d/attribsem.o,
	d/common-charactertables.o, d/common-identifiertables.o.
	* d-attribs.cc (apply_user_attributes): Update for new front-end
	interface.
	* d-builtins.cc (d_init_versions): Predefine CppRuntime_GNU.
	* d-incpath.cc (add_globalpaths): Update for new front-end interface.
	(add_filepaths): Likewise.
	(add_import_paths): Likewise.
	* d-lang.cc (d_post_options): Likewise.
	* dmd/MERGE: Merge upstream dmd c11e1d1708.
	* dmd/VERSION: Bump version to v2.108.1.

libphobos/ChangeLog:

	* libdruntime/MERGE: Merge upstream druntime e60bfd11bd.
	* src/MERGE: Merge upstream phobos 8729740e3.

gcc/testsuite/ChangeLog:

	* gdc.dg/torture/pr96435.d: Add dg-warning.