openbsd: ensure we link to the built libperl.a, not the system libperl.a

When building with gcc, lib/ExtUtils/t/Embed.t would link against
the system libperl.a rather than the newly built libperl.a.

Due to the limited API used by the sample code this typically didn't
crash, but some configuration changes could result in a crash or a
link error.

For OpenBSD, change the link options to more closely match those
used when building the perl executable, which results in linking
against the correct library.

Fixes Perl#22125

Author: tonycoz

lib/ExtUtils/t/Embed.t

@@ -103,13 +103,26 @@ if ($^O eq 'VMS') {
    elsif ($^O eq 'os390' && $Config{usedl}) {
     push(@cmd,"-L$lib", ldopts());
    } else { # Not MSWin32 or OS/390 (z/OS) dynamic.
-    push(@cmd,"-L$lib",'-lperl');
+    my $ldopts = ldopts();
+    if ($^O eq 'openbsd' && $Config{useshrplib} eq "false") {
+        # see github #22125
+        # with OpenBSD, the packaged gcc (tries to) link
+        # against the system libperl, this will be fine once
+        # this perl gets installed, but that's not so good when
+        # testing against the uninstalled perl.
+        # This also matches how Makefile.SH links the perl executable
+        push @cmd, "$lib/libperl.a";
+        $ldopts =~ s/ -lperl\b//;
+    }
+    else {
+        push(@cmd,"-L$lib",'-lperl');
+    }
     local $SIG{__WARN__} = sub {
 	warn $_[0] unless $_[0] =~ /No library found for .*perl/
     };
     push(@cmd, '-Zlinker', '/PM:VIO')	# Otherwise puts a warning to STDOUT!
 	if $^O eq 'os2' and $Config{ldflags} =~ /(?<!\S)-Zomf\b/;
-    push(@cmd,ldopts());
+    push(@cmd, $ldopts);
    }
 
    if ($^O eq 'aix') { # AIX needs an explicit symbol export list.
@@ -158,7 +171,7 @@ $embed_test = "run/nodebug $exe" if $^O eq 'VMS';
 print "# embed_test = $embed_test\n";
 $status = system($embed_test);
 print (($status? 'not ':'')."ok 10 # system returned $status\n");
-#unlink($exe,"embed_test.c",$obj);
+unlink($exe,"embed_test.c",$obj);
 unlink("$exe.manifest") if $cl and $Config{'ccversion'} =~ /^(\d+)/ and $1 >= 14;
 unlink("$exe$Config{exe_ext}") if $skip_exe;
 unlink("embed_test.map","embed_test.lis") if $^O eq 'VMS';
@@ -196,7 +209,7 @@ int main(int argc, char **argv, char **env) {
     perl_construct(my_perl);
     PL_exit_flags |= PERL_EXIT_WARN;
 
-    PERL_API_VERSION_CHECK;
+    PERL_API_VERSION_ASSERT;
 
     my_puts("ok 3");