#4763 (ok 4.3.10) database export with more then cca 512 tables fails

[PaveXK]

When trying to export database with 543 tables, the export fails and moreover is followed by immediate logout, so its not possible to even report it using default ajax settings (ask).
When I select less then approx. 500 tables, the export works ok so the number 512 is educated guess. Default export settings used.

PMA versions affected: 4.3.0-4.3.9
PMA versions not affected: 4.2.13.1 and presumably older
Server software: MySQL 5.5.34, IIS 7.5, PHP 5.4.37
php max_input_vars = 1000