Test suite: added support for the Debian distribution.

* Replaced the shell interpreter with bash to run
  the script test/zdtm.sh correctly.

* Added new directories into the routine contruct_root()
  searched by the Debian version of the dynamic linker.

Signed-off-by: Alexander Kartashov <alekskartashov@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>