Make android_app_import multi targets arch module.

This makes it consistent with android_app. Also, most android_app_import
modules with JNI libs target a single arch.

(This is a cherry-pick change.)

Test: TreeHugger
Bug: 154281342
Change-Id: I5bbb2d2b733bbd6b868898285683ba5ff45be10b
Merged-In: I5bbb2d2b733bbd6b868898285683ba5ff45be10b