Enable TAP tests of pg_receivewal for ZLIB on Windows, take three

This reverts commit 6a2c532.  fairywren and bowerbird failed those tests
because of incorrect versions of ZLIB linked to, causing errors like
SIGBREAKs that stopped buildfarm runs or EACCES failures when writing
compressed WAL segments.

Andrew Dunstan has done all the investigation here, so he deserves all
the credit for being able to enable those tests on Windows.

Discussion: https://postgr.es/m/9040d5ed-6462-66a4-07ac-2923785ae563@dunslane.net

Author: michaelpq

src/bin/pg_basebackup/t/020_pg_receivewal.pl

@@ -72,13 +72,11 @@
 my @partial_wals = glob "$stream_dir/*\.partial";
 is(scalar(@partial_wals), 1, "one partial WAL segment was created");
 
-# Check ZLIB compression if available.  On Windows, some old versions
-# of zlib can cause some instabilities with this test, so disable it
-# for now.
+# Check ZLIB compression if available.
 SKIP:
 {
-	skip "postgres was not built with ZLIB support, or Windows is involved", 5
-	  if (!check_pg_config("#define HAVE_LIBZ 1") || $windows_os);
+	skip "postgres was not built with ZLIB support", 5
+	  if (!check_pg_config("#define HAVE_LIBZ 1"));
 
 	# Generate more WAL worth one completed, compressed, segment.
 	$primary->psql('postgres', 'SELECT pg_switch_wal();');