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
libc & libm: use hard float

Summary: This change does not require a global float abi change, or multi lib changes. This shouldn't affect anything using assembly that greatly, meaning it might be good to readdress performance differences between some c and assembly routines.

Test Plan: Stability on all devices should be confirmed as well as math and bionic performance.

Reviewers: Mustaavalkosta, michyprima, randall.rushing, rlasalle15, synergy

Reviewed By: synergy

Differential Revision: http://review.codefirex.com/D68