Support Android V 16kb page sizes

[briansmith]

See https://github.com/android/ndk/wiki/Changelog-r27#announcements:

Android V will allow OEMs to ship arm64-v8a devices with 16KiB page sizes. Devices that use this configuration will not be able to run existing apps that use native code. To be compatible with these devices, applications will need to rebuild all their native code to be 16KiB aligned, and rewrite any code which assumes a specific page size. ndk-build and CMake have options to enable this mode (see note about APP_SUPPORT_FLEXIBLE_PAGE_SIZES and ANDROID_SUPPORT_FLEXIBLE_PAGE_SIZES below). A future version of the NDK will enable this mode by default. If you're using or maintaining a third-party build system, consult the build system maintainers guide for instructions.

See Support 16 KB page sizes for more information.

Not sure if any action is needed here but I'm going to track this with an issue just in case. Help appreciated.