Add shebang to the art script.

Because there are still some that don't use bash as login shell.

Also fix /bin symlink in the chroot setup, like in the real root.

Test: Golem-style art invocation with silvermont target
Test: Vogar tests (run-libcore-tests.sh), which use the art script, in
  chroot on device
Test: m out/host/linux-x86/bin/art && \
      out/host/linux-x86/bin/art -showversion
  with shebang "#!/bin/sh" and "#!/usr/bin/posh" (Policy-compliant
  Ordinary SHell)
Change-Id: I7445b07f121eaa947e187ab822c7c098d5957f92
3 files changed