[BUGFIX] Change sys_file.size type from INT to BIGINT

Regular INT limits filesize to 2GB.

Change-Id: I525bd53bff6495630bd5880c8ef8789a1d9bbf26
Resolves: #60327
Releases: 6.3, 6.2
Reviewed-on: http://review.typo3.org/31752
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>