scripts/get_maintainer.pl: don't deduplicate unnamed addresses ie: mailing lists

Fix a defect with the first mailing list address being used for each
subsequent mailing list.

Updated to 0.26-beta6.

Signed-off-by: Joe Perches <joe@perches.com>
Cc: Florian Mickler <florian@mickler.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>