从 12.04 升级到 14.04 后，多个 Perl 软件包停止工作。
例如，cpan给我：
Attempt to reload Scalar/Util.pm aborted.
Compilation failed in require at /usr/local/share/perl/5.18.2/CPAN/Meta/Requirements.pm line 35.
BEGIN failed--compilation aborted at /usr/local/share/perl/5.18.2/CPAN/Meta/Requirements.pm line 35.
Compilation failed in require at /usr/share/perl/5.18/CPAN/Distribution.pm line 7.
BEGIN failed--compilation aborted at /usr/share/perl/5.18/CPAN/Distribution.pm line 7.
Compilation failed in require at /usr/share/perl/5.18/CPAN.pm line 25.
BEGIN failed--compilation aborted at /usr/share/perl/5.18/CPAN.pm line 25.
Compilation failed in require at /usr/share/perl/5.18/App/Cpan.pm line 219.
BEGIN failed--compilation aborted at /usr/share/perl/5.18/App/Cpan.pm line 219.
Compilation failed in require at …