Add __aeabi_idiv to the dummy reference list.

If the platform code is compiled with -mcpu=cortex-a15, then without this
change prebuilt libraries built against -march=armv7 cannot resolve the
dependency on __aeabi_idiv (provided by libgcc.a).

Bug: 7961327

cherry-picked from internal master.

Change-Id: I8fe59a98eb53d641518b882523c1d6a724fb7e55