use $GC, $GL in gotest, to match gccgo's gotest.
use $GC, $GL in gotest, to match gccgo's gotest.

use $GC in all_test.go for portability.

R=r
DELTA=19  (12 added, 0 deleted, 7 changed)
OCL=23305
CL=23325
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go