pgsql: Avoid calling TestLib::perl2host on a symlinked directory

Avoid calling TestLib::perl2host on a symlinked directory

Certain versions of msys2/Windows have been observed to resolve symlinks
in perl2host rather than just follow them. This defeats using a
symlinked shorter path to a longer path, and makes certain tests fail.
We therefore call perl2host on the parent directory of the symlink and
thereafter just use that result.

Apply to release 14 where the problem has been observed.

Branch
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REL_14_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/c42d3d04d7d03782ae179bf92ea0eb9f2fa8f409

Modified Files
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src/bin/pg_basebackup/t/010_pg_basebackup.pl | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)