test: adjust 'cd' regexpr to match an optional canonically pathname

test: adjust 'cd' regexpr to match an optional canonically pathname

New regexpr now correctly deals with trailing canonical pathname.

Before only the following output was matched:
(gdb) cd
Working directory /users/foo

In addition it now matches an optional trailing canonical pathname:
(gdb) cd
Working directory /users/foo
 (canonically /nfs/users/foo).

Triggered by `realpath .` != `pwd`

2013-09-10  Sanimir Agovic  <sanimir.agovic@intel.com>

testsuite/
	* gdb.base/default.exp: Adjust regexpr for 'cd' to match optional
	canonical pathname.