[C] Change distanceFromSpawn >= spawnSize to distanceFromSpawn > spawnSize, Fix BUKKIT-4154

### The Issue

With spawn-protection=16, breaking is prevented in a 33 by 33 block area, placing is prevented in a 31 by 31 block area.

### What this PR does

This changes `distanceFromSpawn >= spawnSize` to `distanceFromSpawn > spawnSize`. If the operator were `>=`, the code would return `true` even if the player
was (assuming `spawnSize` was 16) 16 blocks from spawn. This code returns
true after the player is at least 17 block away from spawn.

### Testing

Tested on a whitelist server, with ops other than me, with no plugins. The player cannot place blocks on the furthermost protected blocks from spawn (i.e. the 16th block from spawn with default settings), when on the newest development build provided to the public, you can.

### Files

Source: https://github.com/jontturi/CraftBukkit/tree/spawnprotectionbuilding
Binary: https://dl.dropboxusercontent.com/u/53997928/github/dl/craftbukkit-1.6.2-R0.1-SNAPSHOT.jar

### Leaky Ticket

https://bukkit.atlassian.net/browse/BUKKIT-4154 (the reporter has done some testing on how long this issue has persisted, you might be interested to see the ticket)