Don't use -rpath on macOS. The Portfile only applies this patch when the
deployment target is earlier than 10.5 since those earlier systems don't have
rpath.

Fixes:

    gmake: *** No rule to make target 'all'.  Stop.

which is caused by the configuration failing to make a Makefile because:

    Expat must be installed prior to building XML::Parser and I can't find
    it in the standard library directories. Install 'expat-devel' (or
    'libexpat1-dev') package with your OS package manager. See 'README'.

which we can see if we add debugging output to CheckLib is caused by:

    ld: -rpath can only be used when targeting Mac OS X 10.5 or later
    collect2: ld returned 1 exit status

https://github.com/cpan-authors/XML-Parser/issues/103
https://github.com/mattn/p5-Devel-CheckLib/issues/40
--- inc/Devel/CheckLib.pm.orig	2023-12-28 13:47:02.000000000 -0600
+++ inc/Devel/CheckLib.pm	2024-11-30 02:23:00.000000000 -0600
@@ -295,7 +295,6 @@
 	    $cfile,
 	    (!defined $lib ? () : (
 	      (map "-L$_", @$libpaths),
-	      ($^O eq 'darwin' ? (map { "-Wl,-rpath,$_" } @$libpaths) : ()),
 	      "-l$lib",
 	    )),
 	    @$ld,