pgsql: meson: Avoid PATH bloat from NLS .mo targets in tmp_install test

meson: Avoid PATH bloat from NLS .mo targets in tmp_install test

On Windows, meson adds the build directory of every target in a test's
'depends:' to that test's PATH. tmp_install depended on
installed_targets, which with NLS enabled includes several hundred .mo
targets, pushing PATH past the Windows length limit. tmp_install and
initdb_cache then failed with no output.

Fix by depending on a stamp custom_target that itself depends on
installed_targets. Meson doesn't walk a custom_target's dependencies
when building the test PATH, so this adds at most one entry. This can
be removed once we mandate a meson version containing the upstream fix
(expected in 1.13).

Reviewed-by: Tristan Partin <tristan(at)partin(dot)io>
Backpatch-through: 16
Discussion: https://postgr.es/m/CAD5tBcJXAX8bz5q9ngE4znvVLiXaPO89D0yTFhJgEPrPyT-Erw@mail.gmail.com

Branch
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REL_19_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/ab5a39e1672e28b59e7699b6d8f461ef9f4b3874

Modified Files
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meson.build | 19 ++++++++++++++++++-
1 file changed, 18 insertions(+), 1 deletion(-)