Chaquopy: Python 2 for Android

Aug 2, 2018

Demo app:
* No changes except for the SDK update.

SDK:
* Fix pip issues involving packages with optional native components.
* Work around inability of Android dynamic linker on API 22 and older to load multiple modules with the same basename.
* Fix ctypes.pythonapi and sys.abiflags, and provide partial implementation of sysconfig.get_config_vars.
* Fix native crash in lrintf / feholdexcept / fegetenv.
* Fix pkgutil.get_data when used with extractPackages.