BUG/MINOR: server: re-align state file fields number

BUG/MINOR: server: re-align state file fields number

Since commit 3169471964fdc49963e63f68c1fd88686821a0c4 ("MINOR: Add
server port field to server state file.") max_fields was not increased
on version number 1. So this patch aims to fix it. This should be
backported as far as v1.8, but the numbering should be adpated depending
on the version: simply increase the field by 1.

Signed-off-by: William Dauchy <wdauchy@gmail.com>
(cherry picked from commit 38cd986c54975add4e14ef0f693dff494e36336d)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>