- Update to 4.0.20:
* initialize directory entries to 0
* bad message "Too few sectors" replaced with "Too many sectors"
* apostrophe in mlabel no longer causes generation of long entry
* option to fake system date for file creation using the
SOURCE_DATE_EPOCH environment variables
* can now be compiled with "clang" compiler
* fallback function for strndup, for those platforms that don't have it
* fixed a number of -Wextra warnings
* new compressed archive formats for uz/lz
* allow to specify number of reserved sectors for FAT32.
* file/device locking with timeout (rather than immediate failure)
* fixed support for BPB-less legacy formats.
* removed check that disk must be an integer number of tracks.
* removed .eh/.oh macros from manual pages (forwarded request 649021 from mloviska)