Reduce code complexity by adding a utility function for reading text
files based on a variable path.
Note: chzdev/lszdev tools apply special path-handling via command line
option --base to allow redirecting hard-coded paths therefore libutil's
util_file functions cannot easily be used.
Reviewed-by: Vineeth Vijayan <vneethv@linux.ibm.com>
Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>