Allocate user array dynamically

[yarrick]

From Samuel Thibault:

Is there a reason for making the 'users' array a fixed-length array rather than an allocated array? My router has very little memory, and the default (using 6MiB) is too much, I had to change the source to change it. Making it an allocated array would permit to change the number of users at runtime for very little extra overhead (const pointer addressing vs variable pointer addressing).

[yarrick]

Fixed in android patch.