Use ccache with poudriere

Summary:
This is expected to speed up a lot two scenarii:

• build of base dependencies like pkg, gettext
• rebuild of same ports

Ref T2039

Test Plan:

• Clear repository to avoid old hashes per directories
• Deploy to WindRiver
• Run port build watching /var/cache/ccache, files was added to cache
• Run again the port build, time decreased from 28" to 18"

Reviewers: DorianWinty

Reviewed By: DorianWinty

Maniphest Tasks: T2039

Differential Revision: https://devcentral.nasqueron.org/D3486