Clean up build system, add .gitignore.

[ericonr]

Removed the chkshsgr and systype checks. This one is still a bit WIP. Technically, chkshsgr checks if the build system can adequately run the hasshsgr test, so just removing it isn't the the best policy.

How should we alter the build style? Should it be made to support only platforms that we do / reasonably modern platforms, eliminating the need for all the choose checks we are doing, or should it be made to still work with all the platforms it originally did?