TEST: Make test/recipes/01-test_symbol_presence.t more platform agnostic

Assuming ".so" as shared library ending is faulty on MacOS, where the
normal shared library extension is ".dylib".

We use the platform module to get the same extension as the build process.

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/15771)

test/recipes/01-test_symbol_presence.t

@@ -9,10 +9,16 @@
 
 use strict;
 use File::Spec::Functions qw(devnull);
-use OpenSSL::Test qw(:DEFAULT srctop_file bldtop_dir bldtop_file);
+use OpenSSL::Test qw(:DEFAULT srctop_file srctop_dir bldtop_dir bldtop_file);
 use OpenSSL::Test::Utils;
 
-setup("test_symbol_presence");
+BEGIN {
+    setup("test_symbol_presence");
+}
+
+use lib srctop_dir('Configurations');
+use lib bldtop_dir('.');
+use platform;
 
 plan skip_all => "Test is disabled on NonStop" if config('target') =~ m|^nonstop|;
 plan skip_all => "Only useful when building shared libraries"
@@ -33,7 +39,7 @@ note
 foreach my $libname (@libnames) {
  SKIP:
     {
-        my $shlibpath = bldtop_file("lib" . $libname . ".so");
+        my $shlibpath = bldtop_file(platform->sharedlib("lib$libname"));
         *OSTDERR = *STDERR;
         *OSTDOUT = *STDOUT;
         open STDERR, ">", devnull();