Package optimizations

[coypu%sdf.org@localhost]

following up:

there's some discussion about whether we should allow packages to have
their own optimization flags.

Reasons for:
1. We will never be able to declare a package as having more than -O2.
Decisions about things like -ffast-math are only possible by people who
regularly modify the code.
We are unnecessarily missing optimizations upstream has tested as OK.

2. Disabling optimizations and relying on CFLAGS, as we currently do,
might be missed if ${CFLAGS} isn't used by mistake.




Unrelated points, IMO:
1. If it makes a package less portable than possible, like
-march=native, we disable this (typically, package builders are
newer than the baseline support people would like to offer)

2. If someone has a problem, we can disable optimization with hacks.mk.
I can assist with any GCC-related problem.