genassym.sh(8) on OpenBSD

The text 6b1d4b7876f3, as OpenBSD 4.1, OpenBSD 4.0, OpenBSD 3.9, OpenBSD 3.8, OpenBSD 3.7, OpenBSD 3.6, OpenBSD 3.5, OpenBSD 3.4 shipped it.

emit an assym.h file