[Issue 21053] Test Suite run.d is built with compiler under test, must be build with bootstrap dmd

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=21053

moonlightsentinel at disroot.org changed:

           What    |Removed                     |Added
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                 CC|                            |moonlightsentinel at disroot.o
                   |                            |rg

--- Comment #2 from moonlightsentinel at disroot.org ---
Partially, it's done for all CI which have an appropriatly recent host
compiler, otherwise it falls back to the generated dmd. This affects a few CI
machines which will update to an appropriate compiler eventually once we raise
the minimally required bootstrap version.

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