We haven't done this in a while. This also tests more codepaths in
in the previous Python 3 update.
libc++ required a few more build tweaks. Also the CMake update was
necessary to update the NDK. Older CMake cannot detect CMAKE_LINKER
in the newer NDK.
Change-Id: I59ab1c6b074b805dd4b8a6ab596c4cf469d5bfa9
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/50167
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>