Fix one build error for the pep build
Fix one build error for the pep build

Fixes the "LOCAL_SRC_FILES points to a missing file" error caused by
the newer NDK version 12.

(the NDK sets APP_ABI to include arm64-v8a, for which it then expects
to have a libetpan build for, but libetpan hardcodes the list of targets)

f-droid/fdroiddata,f-droid/fdroiddata,f-droid/fdroid-data