add a function to determine if we're running on Android
add a framebuffer module for Android
start input abstraction for Android
standalone toolchain should be platform android-9, small fix

The standalone toolchain for Android builds should be for platform
android-9, since we will build LuaJIT for that, too.

Also, don't build the Lua/C module "koreader-input" for Android
builds.
Merge pull request #165 from hwhw/android

Android