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.

gdb/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2013-09-10  Sanimir Agovic  <sanimir.agovic@intel.com>
+
+	* gdb.base/default.exp: Adjust regexpr for 'cd' to match optional
+	canonical pathname.
+
 2013-09-04  Doug Evans  <dje@google.com>
 
 	* gdb.python/py-events.py (exit_handler): Verify we get the expected

gdb/testsuite/gdb.base/default.exp

@@ -83,7 +83,7 @@ gdb_test "call" "The history is empty..*" "call"
 gdb_test "catch" "Catch requires an event name..*" "catch"
 
 #test cd
-gdb_test "cd" "Working directory \[^\r\n\]*\\."
+gdb_test "cd" "Working directory \[^\r\n\]*\(\r\n \\(canonically \[^\r\n\]*\\)\)?\\."
 
 #test clear
 gdb_test "clear" "No source file specified..*" "clear"