Strip any version comparison operator from the 'perl' build requirement

Because cpanspec does things with the epoch, and already adds version
comparison operators itself, they should be stripped from whatever
META.yml specifies so cpanspec does not generate invalid spec files.

cpanspec

@@ -1015,6 +1015,7 @@ END
     }
 
     if (defined($build_requires{perl})) {
+        $build_requires{perl} =~ s/^[<>=]+ *//;
         printf $spec "%-16s%s >= %s\n", "BuildRequires:", "perl",
             (($build_requires{perl} lt "5.6.0" ? "0:" : "1:")
             . $build_requires{perl}) if $build_requires{perl};