libvpx

Remove asm offset dependencies

The obj_int_extract code is no longer worth maintaining. It creates
significant issues when adapting for different build systems and no
longer offers as significant of a performance benefit due to
improvements in intrinsics.

Source files will remain until the various third-party builds are updated.

The neon fast quantizer has been moved to intrinsics. The armv6 version
has been removed because so few remaining targets require it.

Compilers and processors have improved significantly since the
pack_tokens code was written. The assembly is no longer faster than the
C code.

pack_tokens were the only optimizations for the armv5te targets so the targets
will be removed after the test infrastructure has been updated.

BUG=710

Change-Id: Ic785b167cd9f95eeff31c7c76b7b736c07fb30eb