More aapt2 aar prebuilt fixes

Ensure aar/res exists, otherwise aapt2 may fail with an error.

Bug: 33381544
Test: Attempt to build aar prebuilt
Change-Id: Ifbeed546fe1a3a48c3dae33f95b04acc559f5b30
Merged-In: Ifbeed546fe1a3a48c3dae33f95b04acc559f5b30
(cherry picked from commit 7a1ad6c8a06b5a328c8a59667e3980ed158d47fa)
1 file changed