Recognize NDK version 19

[wjmelements]

Changes

Each new NDK version will break under this scheme.
This fixes the error Unknown ndk version: 19.0.5232133.
Please develop a long-term solution.
Reviewer @ttsugriy

[wjmelements]

This approach is similar to #1511

[wjmelements]

Please either merge this or #2190

[ttsugriy]

sorry, I no longer work on Buck, but I'm sure someone from the Buck team, like @styurin will take a look soon.

[wjmelements]

Another thing I noticed is that NDK 19 removed the -gcc scripts in ndk-bundle/toolchains/arm-linux-androideabi-4.9/prebuilt/darwin-x86_64/bin/ (android/ndk#862).

[wjmelements]

Thus NDK 19 is not fully supported by this PR.

The error is

~/Library/Android/sdk/ndk-bundle/toolchains/arm-linux-androideabi-4.9/prebuilt/darwin-x86_64/bin/arm-linux-androideabi-gcc doesn't exist.

The files in that directory are:

arm-linux-androideabi-addr2line arm-linux-androideabi-dwp       arm-linux-androideabi-ld.bfd    arm-linux-androideabi-objdump   arm-linux-androideabi-strings
arm-linux-androideabi-ar        arm-linux-androideabi-elfedit   arm-linux-androideabi-ld.gold   arm-linux-androideabi-ranlib    arm-linux-androideabi-strip
arm-linux-androideabi-as        arm-linux-androideabi-gprof     arm-linux-androideabi-nm        arm-linux-androideabi-readelf
arm-linux-androideabi-c++filt   arm-linux-androideabi-ld        arm-linux-androideabi-objcopy   arm-linux-androideabi-size

I am not sure how to best fix this breakage.

[styurin]

Adding support for the next version NDK is not simply bumping the version, there are usually major changes which needs to reflected before enabling that support.

[wjmelements]

I documented some of the incompatibility in #2191. Closed because I do not have the time to investigate this myself.