* SDK tools is upgraded to 27.0.0.
- Refactored to use `sdkmanager`/`avdmanager` instead of the deprecated
`android` tool.
* The Java version used by Android SDK is downgraded to OpenJDK-8, in order
to download the SDK through HTTPS.
* NDK is upgrade to r15c.
- Dropped support for android-9 (2.3 / Gingerbread), the minimal
supported version is now android-14 (4.0 / Ice Cream Sandwich).
- Changed the default Android compiler from GCC to clang.
- For details of change introduced by NDK r15, see
https://github.com/android-ndk/ndk/wiki/Changelog-r15.
Apparently the https urls are broken due to some certificate validation
whatnots, and so far the least intrusive solution I've found is to just disable
that.
Use the `-f` flag to indicate that, for example, a 500 response code is to be
considered a failure, triggering the normal retry logic. Also ignore errors
where we check the date from google.com, as a failure there shouldn't fail the
build.
