Avoid unused variable warning when NDEBUG.

Author: scottmg@chromium.org
Review URL: https://codereview.appspot.com/134650043

git-svn-id: http://libphonenumber.googlecode.com/svn/trunk/cpp/src/phonenumbers@700 ee073f10-1060-11df-b6a4-87a95322a99c
1 file changed