gcov.c (md5sum_to_hex): Fix output of MD5 hex bytes.

2017-03-31  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        * gcov.c (md5sum_to_hex): Fix output of MD5 hex bytes.
        (make_gcov_file_name): Use the canonical path name for generating
        the MD5 value.
        (read_line): Fix handling of files with ascii null bytes.

From-SVN: r246605