test/recipes/02-err_errstr: skip errors that may not be loaded on Windows

Fixes #8091

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/8094)

test/recipes/02-test_errstr.t

@@ -38,6 +38,43 @@ plan skip_all => 'OpenSSL is configured "no-autoerrinit" or "no-err"'
 # (this is documented)
 my @posix_errors = @{$Errno::EXPORT_TAGS{POSIX}};
 
+if ($^O eq 'MSWin32') {
+    # On Windows, these errors have been observed to not always be loaded by
+    # apps/openssl, while they are in perl, which causes a difference that we
+    # consider a false alarm.  So we skip checking these errors.
+    # Because we can't know exactly what symbols exist in a perticular perl
+    # version, we resort to discovering them directly in the Errno package
+    # symbol table.
+    my @error_skiplist = qw(
+        ENETDOWN
+        ENETUNREACH
+        ENETRESET
+        ECONNABORTED
+        EISCONN
+        ENOTCONN
+        ESHUTDOWN
+        ETOOMANYREFS
+        ETIMEDOUT
+        EHOSTDOWN
+        EHOSTUNREACH
+        EALREADY
+        EINPROGRESS
+        ESTALE
+        EUCLEAN
+        ENOTNAM
+        ENAVAIL
+        ENOMEDIUM
+        ENOKEY
+    );
+    @posix_errors =
+        grep {
+            my $x = $_;
+            ! grep {
+                exists $Errno::{$_} && $x == $Errno::{$_}
+            } @error_skiplist
+        } @posix_errors;
+}
+
 plan tests => scalar @posix_errors
     +1                          # Checking that error 128 gives 'reason(128)'
     +1                          # Checking that error 0 gives the library name