Fix change in logic introduced in https://r.android.com/1666563.

https://r.android.com/c/platform/build/soong/+/1666563/3/cc/image.go#551
introduced a change in logic.

Bug: 188717568

Test: source build/envsetup.sh
Test: m -j nothing
Change-Id: Iab27f1c3ca1a488d074f9c5c61fe071d7d445b91