android/utils/host_bitness.c: android_getHostBitness()

This patch moves the host bitness detection code to android/utils/
and also improves it to work properly on Windows, in preparation for
Win64 executables.

+ Ensure 'emulator' launcher uses it.
+ Add basic unit test.

Change-Id: I7d55397efeb749b72c502241c4da4cd16696c082
6 files changed