cmake: No longer define _GLIBCXX_DEBUG for gcc debug.

gtest's static registration fires off before main and uses stdlib
containers. Apparently some part of the debug containers option
requires init out of main, too, because it crashes outside of main
under gtest in stdlib.

Useful as debug containers may be, if we can't get around a crash,
we can't use them.
cmake: Bashed silliness in axiom-env.

axiom-env had a dependency on an undefined boost project. I'm not sure
how this even built. Meh. Changed it to just use boost's include.
Shelled env test.
env: Added test for semver.