release/packages/Makefile.package: Fix typo

"librairies" --> "libraries"

Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Pull Request: https://github.com/freebsd/freebsd-src/pull/553
(cherry picked from commit 04912a8d1c15f9771545059032eedb9b0fea6e70)