Remove those includes which are searched for portably.

ok stsp

This approach uses more memory but is much faster. To offset the additional memory usage somewhat the cache now stores very small deltas only. However, overall memory usage goes up. Hopefully we will find a way to reduce this later. ok op@

This adds the capability to compile got-portable on FreeBSD.

This commit modifies the GoT main branch to be able to compile it under linux.