[asan] Support 'su' rooted devices in ASan setup script.

Android devices may not support 'adb root', but be rooted with 'su'
binary. This patch makes it possible to install ASAN to such
devices. When --use-su flag is specified, most 'adb ...' commangs are
changed to 'adb su -c "..."'.

Some other notes:
 * 'readlink' changed to 'ls -l', since not all devices have readlink
   in their firmware.
 * removing ASan library step moved to very end, because 'su' may not
   run properly without this library until shell will be restarted.

Patch by Dmitry <ripp at yandex-team dot ru>.

llvm-svn: 229368