Merge branch '141-fix-android-build-win-64' into 'master'

Fix Android build script on Windows 64 bit (NDK r10e)

- Correct Host OS name on Windows 64 bit in common.py
- Add the missing Host OS in toolchain file for NDK r10e
- Downgrade to LLVM 3.5 in NDK r10e because the prebuilt version 3.6 is
  missing the llvm-ar utility which is needed by the build script.

See merge request !236