pgsql: ci: Test Windows + Mkvcbuild.pm in REL_16_STABLE.

ci: Test Windows + Mkvcbuild.pm in REL_16_STABLE.

* REL_15_STABLE introduced CI and tested Windows with Mkvcbuild.pm.
* REL_16_STABLE introduced Meson and switched Windows CI to that.
* REL_17_STABLE dropped Mkvcbuild.pm.

That left a blind spot when testing Makefile changes back-patched into
16. Mkvcbuild.pm scrapes Makefiles and might break, so it's useful to
be able to check that before hitting "hamerkop" in the build farm.

Copy REL_15_STABLE's Windows task into REL_16_STABLE as a separate task,
with a few small adjustments to match later task definition style.

Discussion: https://postgr.es/m/CA%2BhUKG%2B-d0OyLMdMiZ%2BFtj2hhZXT%2B0HOyHfrPBecE_vZzh9rRg%40mail.gmail.com

Branch
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REL_16_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/4b9ce1ef609ba5a5eabc41a82d1a3e3710fc663f

Modified Files
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.cirrus.tasks.yml | 111 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 111 insertions(+)