Compile native sources for arm64

[KevinBaragonaIJKCO]

This makes it work on arm64 devices. Fixes #105 for me...

[saki4510t]

Sorry for my answer delay and thank you for providing pull request.

Your issue came from that you mixed libraries that have 64 bits binary with the libraries that have no 64 bits binary.
Please check WiKi How to exclude native binaries for specific architecture(s)

If you really need 64 bits binaries, I feel it will be better to use APP_ABI := all because your pull request can't solve similar issue for x86_64 & mips64 architectures.
APP_ABI := all generates libraries for all architectures supported by current NDK.
So could you change to?

[saki4510t]

As I wrote on How to exclude native binaries for specific architecture(s), I don't want to build this repository for 64 bit architectures as default setting.

[muojp]

I read through https://github.com/saki4510t/UVCCamera/wiki/How-to-exclude-native-binaries-for-specific-architecture(s) doc. Unfortunately, time passed and situation changed due to Google's new policy announced in December 2017.

https://android-developers.googleblog.com/2017/12/improving-app-security-and-performance.html

64-bit binary will be required for new and updated apps. We need to be ready against the new policy before August 2019, so it would be a suitable time for reconsideration and polishing.

[muojp]

I composed a new pull-req for this: #412

@saki4510t could you please review the pull-req?