support 64 bit ints in a32 backend through neon instructions

[robertmuth]

Reference:

https://community.arm.com/developer/tools-software/oss-platforms/b/android-blog/posts/arm-neon-programming-quick-reference

Most operations are support except division: https://community.arm.com/developer/tools-software/tools/f/armds-forum/930/division-with-neon