Ensure support for files larger than 2GB

Feel free to close this issue if we feel it's a duplicate, but there seems to be little movement in these other related issues:

#1815886: Drupal core cannot manage files larger than 4 GB
#1651096: Adding file metadata to {amazons3_file} fails with filesize > 2GB, use BIGINT instead
#1003692: PDOException: SQLSTATE[22003] after entering large value in integer and decimal field

The third issue, however, appears to be geared towards number fields only with regard to the Field API; therefore I believe we'll need to either work on getting the Drupal core issue solved, or find a workaround.

TLDR: it does not seem to matter what value we enter into the "max filesize" field of a Commerce File product field; the {file_managed} table remains an INT(10) which fails on values inserted for files larger than 2GB. For our site, we have MPG and ISO files that are generally over this limit, reaching 4GB (or 8GB for a dual-layer DVD image). This means Drupal cannot serve as a file management system for video production websites like ours in its current form.

My proposal would be to hook the Commerce File (and Amazons3) fields into a function that makes sure the requisite tables' fields are the correct size. For instance, using Commerce File with AmazonS3 and my AmazonS3 (Filefield Sources) Reference integration, I would alter the module to look for an update to the "max filesize" attribute, and when executed, would alter the newly-introduced {amazons3_file} cache table for that module. Otherwise, attempting to migrate (or upload) files larger than 2GB results in this error:

SQLSTATE[22003]: Numeric value out of range: 1264 Out of range value for column 'filesize' at row 1: INSERT INTO {file_managed} (uid, filename, uri, filemime, filesize, status, [error]
timestamp, type) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2, :db_insert_placeholder_3, :db_insert_placeholder_4, :db_insert_placeholder_5,
:db_insert_placeholder_6, :db_insert_placeholder_7); 

Any ideas are welcome, as right now I am simply altering our schema, hoping this doesn't result in any future conflicts.