Merge "run-as: improve error messages."

  std::string seinfo = std::string(info.seinfo) + ":fromRunAs";

  if (selinux_android_setcontext(uid, 0, seinfo.c_str(), pkgname) < 0) {

    error(1, errno, "couldn't set SELinux security context");

    error(1, errno, "couldn't set SELinux security context '%s'", seinfo.c_str());

  }

  // cd into the data directory, and set $HOME correspondingly.

  if (TEMP_FAILURE_RETRY(chdir(info.data_dir)) == -1) {

    error(1, errno, "couldn't chdir to package's data directory");

    error(1, errno, "couldn't chdir to package's data directory '%s'", info.data_dir);

  }

  setenv("HOME", info.data_dir, 1);