illumos gate

Currently, libkvm (and mdb) require both a kernel crash dump (e.g., vmcore.x) and a kernel symbol table (e.g., unix.x) to be specified. The latter of these is an ancient notion, and there is absolutely no reason for it – all of the information needed is already present in the dump. This should be fixed by pulling the symbol table out of the dump and faking up a namelist file, thereby allowing extant software to operate with a minimal amount of change. This change involves modifying libkvm to perform the actual extraction, and then mdb to not require the unix.x file to be specified or present.