Replace multiple 'use vars' by 'our' in dist

Replace multiple 'use vars' by 'our' in dist

Using vars pragma is discouraged and has been superseded
by 'our' declarations available in Perl v5.6.0 or later.

Additionally using 'vars' pragma increase the memory consumption of a
program by about 700 kB for no good reason.

This commit is about replacing the usage of 'vars' pragma
by 'our' in blead where it makes sense. ( leaving 'cpan' directory
outside of the scope )

-- using vars
perl -e 'use vars qw(@ISA $AUTOLOAD $VERSION); print qx{grep RSS /proc/$$/status} '
VmRSS:        2588 kB

-- using our instead
perl -e 'our (@ISA, $AUTOLOAD, $VERSION); print qx{grep RSS /proc/$$/status} '
VmRSS:        1864 kB