dtoh: do not write exact compiler version in silent mode

[wilzbach]

The exact compiler version breaks AUTO_UPDATE and also will require unnecessary updates to frontend.h.

See also: #11679 (comment)

[dlang-bot]

Thanks for your pull request, @wilzbach!

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Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub run digger -- build "master + dmd#11680"

[UplinkCoder]

why does this break anything?

[MoonlightSentinel]

• The generated frontend.h will change with every new release due to this comment.
• compilable/dtoh_***.d use $n$ to avoid this problem but AUTO_UPDATE overwrites special sequences

[wilzbach]

(+ also when people eventually start to generate headers like we do with frontend.h they will run into the same problems).

[MoonlightSentinel]

This change should probably be listed in the existing changelog entry.

[wilzbach]

This change should probably be listed in the existing changelog entry.

Nah. This is implementation detail.

[MoonlightSentinel]

Fair enough