emulator: use 3.18 kernel as default for arm

for arm32 and arm64, use 3.18 kernel as default.
move old ranchu kernel to 3.10; create link to
3.18 kernel.

this is just first step to get arm booting by
emulator, as of now, arm64 has native crash in
surfaceflinger and other services;
arm32 has reboot loop;

Change-Id: I88bf2d40ed382c3aacc4b58da646148e4f3376c3
4 files changed