d: Merge dmd, druntime 4ccb01fde5, phobos eab6595ad

D front-end changes:

	- Added pragma for ImportC to allow setting `nothrow', `@nogc'
	  or `pure'.
	- Mixin templates can now use assignment syntax.

D runtime changes:

	- Removed `ThreadBase.criticalRegionLock' from `core.thread'.
	- Added `expect', `[un]likely', `trap' to `core.builtins'.

Phobos changes:

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

gcc/d/ChangeLog:

	* dmd/MERGE: Merge upstream dmd 4ccb01fde5.
	* Make-lang.in (D_FRONTEND_OBJS): Rename d/foreachvar.o to
	d/visitor-foreachvar.o, d/visitor.o to d/visitor-package.o, and
	d/statement_rewrite_walker.o to d/visitor-statement_rewrite_walker.o.
	(D_FRONTEND_OBJS): Rename
	d/{parsetime,permissive,postorder,transitive}visitor.o to
	d/visitor-{parsetime,permissive,postorder,transitive}.o.
	(D_FRONTEND_OBJS): Remove d/sapply.o.
	(d.tags): Add dmd/common/*.h.
	(d/visitor-%.o:): New rule.
	* d-codegen.cc (get_frameinfo): Update for new front-end interface.

libphobos/ChangeLog:

	* libdruntime/MERGE: Merge upstream druntime 4ccb01fde5.
	* src/MERGE: Merge upstream phobos eab6595ad.