put an mi wrapper around stdarg.h/varargs.h. gcc3 moved stdarg/varargs macros
to built-ins, so eventually we will have one version of these files.
Special adjustments for the kernel to cope: machine/stdarg.h -> sys/stdarg.h
and machine/ansi.h needs to have a _BSD_VA_LIST_ for syslog* prototypes.
okay millert@, drahn@, miod@.