[lld] [LLD][COFF] Display the size of all consumed inputs with /summary (take 2) (PR #157284)

[Alexandre Ganea via llvm-commits]

aganea wrote:

> LGTM, this looks straightforward enough.
> 
> I'm somewhat surprised to see a seemingly general feature like `/summary` (even if many of the numbers may be related to debug info) be implemented in the PDB writer (which obviously is a preexisting design). What if the user doesn't do any PDB output at all (or e.g. links with `-debug:dwarf`) - does the `/summary` option still have an effect?

I initially meant it for some PDB stats, but indeed its scope already goes beyond that. I will move it to a more appropriate place and will send a PR.

https://github.com/llvm/llvm-project/pull/157284