if an object in an archive tries to refer
	to a file in its original source directory,
	ignore it.

* 6ar:
	fix bug if archive is empty.

* gobuild:
	build archive in current directory.

* math:
	use new gobuild Makefile.

* test/math.go:
	rename to mathest.go, add // run line, make it run.

R=r
DELTA=494  (277 added, 203 deleted, 14 changed)
OCL=19090
CL=19171