test-dist-modules.pl: make separate installation the default

This avoids the dangerous default of overwriting installed modules.

Author: tonycoz

.github/workflows/testsuite.yml

@@ -853,5 +853,5 @@ jobs:
         run: /usr/bin/perl -V
       - name: Build and test dist modules
         run:
-          /usr/bin/perl Porting/test-dist-modules.pl -continue -separate
+          /usr/bin/perl Porting/test-dist-modules.pl -continue
 

Porting/test-dist-modules.pl

@@ -11,11 +11,16 @@
 
 my $continue;
 my $separate;
+my $install;
 GetOptions("c|continue" => \$continue,
            "s|separate" => \$separate,
+           "i|install"  => \$install,
            "h|help"     => \&usage)
   or die "Unknown options\n";
 
+$separate
+  and warn "-s / -separate is now the default\n";
+
 $|++;
 
 -f "Configure"
@@ -28,7 +33,7 @@
 
 my @config;
 my $install_path;
-if ($separate) {
+unless ($install) {
     # require EU::MM 6.31 or later
     my $install_base = tempdir( CLEANUP => 1 );
     push @config, "INSTALL_BASE=$install_base";