d: Merge upstream dmd 5cc71ff83, druntime 1134b710

D front-end changes:

 - Fix ICEs that occurred when using opaque enums.

 - Update `pragma(printf)' checking code to work on 16-bit targets.

Phobos change:

 - Don't compile in argTypes code on AArch64

Reviewed-on: https://github.com/dlang/dmd/pull/12378
	     https://github.com/dlang/druntime/pull/3431

gcc/d/ChangeLog:

	* dmd/MERGE: Merge upstream dmd 5cc71ff83.

libphobos/ChangeLog:

	* libdruntime/MERGE: Merge upstream druntime 1134b710.