arm: disable another flaky test.

these tests work fine on n1 and gumstix. it's unclear
why they keep failing on the godashboard build.

R=rsc
CC=golang-dev
https://golang.org/cl/1664056

test/arm-pass.txt

 ./235.go
-# ./64bit.go	# fail, flaky
+# ./64bit.go	# fail, flaky on android build
 ./args.go
 ./assign.go
 ./assign1.go
@@ -430,7 +430,7 @@ fixedbugs/bug239.go
 fixedbugs/bug240.go
 fixedbugs/bug241.go
 fixedbugs/bug242.go
-fixedbugs/bug243.go
+# fixedbugs/bug243.go	# fail, flaky on android build
 fixedbugs/bug244.go
 fixedbugs/bug245.go
 fixedbugs/bug246.go