Add platform 0.4.21: Linux 32-bit ARM with bionic ("Android CLI")
Fix dev-file.c for android

Android don't have S_IREAD and S_IWRITE
Make the S_IREAD/S_WRITE comment slightly more specific

The glibc documentation describes S_IREAD/S_IWRITE as "obsolete
synonym[s] provided for BSD compatibility." Bionic (the libc used on
Android) does not define S_IREAD/S_IWRITE at all.
Merge pull request #191 from earl/build-android-cli

Build CLI binaries for Android. (BrianH: I agree that non-GUI apps will want some of the common libs eventually.)