Logger: Fix handling of absolute paths

This fixes path handling for log files so that an extra / is not
appended to the file path when the path is absolute (begins with /).
This would previously result in different but functionally equivalent
paths in the output of 'logger show channels'.


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/1.8@407455 f38db490-d61c-443f-a65b-d21fe96a405b