travis: reorder matrix to speed up build

travis: reorder matrix to speed up build

The OSX and mingw builds are much slower than the other jobs.  Our free
travis account can only use 4 build executors in parallel. Run the slow
builds earlier, so that when one or more of these finish, the free build
executors will start building the configure variants in parallel with the
slow ones.  (Instead of doing the slow ones last, which results in using
only 1-2 executors during the end stage.)

Signed-off-by: Steffan Karger <steffan@karger.me>
Acked-by: Antonio Quartulli <a@unstable.cc>
Message-Id: <1503220744-5569-1-git-send-email-steffan@karger.me>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg15302.html
Signed-off-by: David Sommerseth <davids@openvpn.net>
(cherry picked from commit e0a6afa12ea14685d0497ab27453ccc2b09e6e1f)