brew-test-bot: install GCC if needed.
arangodb 1.4.7

Closes #26168.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>
pyenv-virtualenv 20140110.1

* Support environment variables of `EZ_SETUP` and `GET_PIP`.
* Support a short option `-p` of `virtualenv`.
* Fix install script

Closes #25784.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>
ffmpeg 2.1.3