Rename HAVE_LINUX_ANDROID_OS -> HAVE_REAL_ANDROID_OS

[DmitrySkiba]

At most of the places, HAVE_ANDROID_OS works for us, so it's defined globally. However, those places where it doesn't work were changed to use HAVE_LINUX_ANDROID_OS. Now I think that HAVE_REAL_ANDROID_OS is a better name.