Merge "Allow boot_variable_file to be read from input_target_files" into main...

Merge "Allow boot_variable_file to be read from input_target_files" into main am: c6e4a86b am: c387972a

Original change: https://android-review.googlesource.com/c/platform/build/+/3062102



Change-Id: Iaf232a1a3369c9d096e05795631b38e7d68ace76
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>