Merge branch 'porting-core-cpan-diff-20210805' into blead

Porting/core-cpan-diff

@@ -53,7 +53,8 @@ Usage: $0 [opts] [ -d | -v | -x ] [ -a | module ... ]
 -d/--diff     Display file differences using diff(1), rather than just
               listing which files have changed.
 
---diffopts    Options to pass to the diff command. Defaults to '-u --binary'.
+--diffopts    Options to pass to the diff command. Defaults to '-u --binary'
+              (except on *BSD, where it's just '-u').
 
 -f|force      Force download from CPAN of new 02packages.details.txt file
               (with --crosscheck only).
@@ -125,7 +126,10 @@ sub run {
           if ( $reverse || $use_diff || $diff_opts );
     }
     else {
-        $diff_opts = '-u --binary' unless defined $diff_opts;
+        #$diff_opts = '-u --binary' unless defined $diff_opts;
+        if (! defined $diff_opts) {
+            $diff_opts = ($^O =~ m/bsd$/i) ? '-u' : '-u --binary';
+        };
         usage("can't use -f without --crosscheck") if $force;
     }