(renamed to avoid any conflict with old p4 copies).

this approach doesn't require auto-generating
files also kept in p4, so it should be easier on
go users who don't sync very often.

this approach will be more work for go developers:
builtin.c needs to be copied to builtin.c.boot in p4
as new functions are added.  mkbuiltin does this
for certain $USERs to help us remember.

R=r
DELTA=343  (176 added, 162 deleted, 5 changed)
OCL=25803
CL=25805