Use existing strcmp prototype if available, even if a local defn
Add support for a "special location," currently used to model errno in a threaded process. Long-term this should be extended to model thread-local storage in general.
Implement support for /model functions/, intended for representing the action of tricky thread-related functions.

Currently used to represent the push-defer / pop-restore mechanism which uses TLS in an unanalysable way. Probably better: factor out the TLS bit and model /that/, but the TLS code is bedded in with the push/pop code in uclibc.