Thread: pgsql: Use native methods to open input in TestLib::slurp_file on Windo

Use native methods to open input in TestLib::slurp_file on Windows.

This is a backport of commits 114541d58e and 6f59826f0 to the remaining
live branches.

Branch
------
REL_12_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/bf88c6d6021c1abbc73197803c98dad0f033b462

Modified Files
--------------
src/test/perl/TestLib.pm | 27 +++++++++++++++++++++++----
1 file changed, 23 insertions(+), 4 deletions(-)