* use new Make.$GOARCH files in gobuild.
* rename 6ar to arch-generic gopack.
* place objects in $GOROOT/pkg/$GOOS_$GOARCH
(makes cross-compiling easier, and no one
ever types these paths by hand anyway).
R=r
DELTA=29 (6 added, 8 deleted, 15 changed)
OCL=29923
CL=29967