do not import testing twice when testing testing.

R=r
DELTA=3  (2 added, 0 deleted, 1 changed)
OCL=35443
CL=35445

src/cmd/gotest/gotest

@@ -107,7 +107,9 @@ importpath=$(make -s importpath)
 	echo
 	# imports
 	if echo "$tests" | egrep -v '_test\.' >/dev/null; then
-		echo 'import "'$importpath'"'
+		if [ "$importpath" != "testing" ]; then
+			echo 'import "'$importpath'"'
+		fi
 	fi
 	if $havex; then
 		echo 'import "./_xtest_"'