* Add instructions to symlink the Android linker.
* Make it clear that paths to `android-ndk-r11c` and `libiconv-libicu-android` may be different based on where the user may have downloaded them by prefixing the paths, such as `/path/to/android-ndk-r11c`.
* Link to https://bugs.swift.org/browse/SR-1321 and recommend Ubuntu 15.10 for now.
* Use HTTPS when invoking `git clone`.
https://bugs.swift.org/browse/SR-1264 identified a problem in the documentation: the `--android-icu-uc` and `--android-icu-i18n` are documented in `utils/build-script` as taking the path to *the directory that contains* the `libcicuuc.so` and `libicui18n.so` libraries, not the paths to the libraries themselves. Passing the path to the libraries themselves causes a build error.
Fix the path to prevent people from encountering an error when copying the build script invocation in the docs.
- Update the documentation to reflect that Swift supports (only)
the latest NDK version. Based on what I've heard from Android
developers that use the NDK, this is a reasonable requirement.
- The most recent version of the Android NDK no longer includes a
"4.8" toolchain version. Change the default to "4.9", and update
the paths in the documentation to match.
- The build script option "--android-ndk-version" was misleading.
This parameter actually refers to the Android API level. Swift
currently supports 21 (Android 5.0) and above (although supporting
lower API levels would be desirable).
Until now the best instructions on how to get started with Swift on
Android were in the original pull request. This spruces those up and
places them in the documentation directory.
