bind/java: give mktemp a template for darwin hosts

Change-Id: I4bf795cfe76daae9a922c671722db3e2fa44a0c0
Reviewed-on: https://go-review.googlesource.com/1320
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>

bind/java/test.bash

@@ -19,7 +19,7 @@ function cleanup() {
 }
 
 if [ -z "$ANDROID_APP" ]; then
-	ANDROID_APP=`mktemp -d` || die 'failed to create a temporary directory'
+	ANDROID_APP=`mktemp -d /tmp/android-java.XXXXX` || die 'failed to create a temporary directory'
 	echo "Temporary directory for test: $ANDROID_APP"
 	trap cleanup EXIT
 fi