checksetup: Don't let cpanm use default cpanfile

In the "cpanm --installdeps [...] ." invocation, cpanm will prefer
loading cpanfile over MYMETA.json, which will cause it to miss
dependencies for features that were enabled on checksetup's command
line. Avoid this by temporarily moving the default cpanfile out of the
way before the cpanm invocation.

Author: CyberShadow

checksetup.pl

@@ -100,7 +100,10 @@ BEGIN
     }
   }
   print "cpanm @cpanm_args \".\"\n" if !$silent;
+  # Ensure cpanm uses MYMETA.json and not cpanfile, in order to correctly resolve features' dependencies
+  rename('cpanfile', 'cpanfile.checksetup');
   my $rv = system('cpanm', @cpanm_args, '.');
+  rename('cpanfile.checksetup', 'cpanfile');
   exit 1 if $rv != 0;
 }