[phobos] std.compiler

[Alex]

Hi,

OK, so I think we need to get rid of std.compiler ASAP. I'm planning
to move all of its code to druntime (core.compiler), as I believe it
makes more sense to have it there (considering std.cpuid was moved
there, for example).

Thus, some questions:

1) Any general objections to this?
2) What do we do about std.compiler? Do we just remove it without
further notice, or do we keep it around and deprecate it?
3) Can we make all variables in core.compiler 'enum'? This would be a
breaking change, but since the module only became useful recently, I
don't think it matters.

If we choose to deprecate std.compiler, then I have the following questions:

1) How should I indicate in std/compiler.d that the module is
deprecated? (I've been told to use pragma(msg, ...).)
2) Is a public import of core.compiler good enough, or do we do
aliasing like we did with std.cpuid -> core.cpuid?

Thanks!

Regards,
Alex