fix(profiles): Move CFLAGS, remove -g, add -mtune=generic

Slowly moving make.conf into profiles, here is another piece. We never
actually use the built debug information so remove -g to produce a
little less of it. Add -mtune=generic to let GCC optimize for whatever
it thinks the most common processors are.
fix(profiles): Enable ipv6 globally because WTF DUH!
Merge pull request #610 from marineam/cflags

Profile maintance