Problem: The getftype() test may fail for char devices if the file
disappeared in between the listing and the getftype() call.
Solution: Ignore empty result. (Ozaki Kiichi, closes#3360)
Problem: Test_existent_file() fails on some file systems.
Solution: Run the test again with a sleep when the test fails without a
sleep. (James McCoy, closes#1984)
Problem: On MS-Windows large files (> 2Gbyte) cause problems.
Solution: Use "off_T" instead of "off_t". Use "stat_T" instead of "struct
stat". Use 64 bit system functions if available. (Ken Takata)
