Don't run mob pickup code on players. Fixes BUKKIT-3150

When a player has canPickUpLoot set to true the code for mob pickup is
triggerd which does not know how to deal with player inventory. Since
players have their own logic for picking up items we simply disable this
code for them.

src/main/java/net/minecraft/server/EntityLiving.java

@@ -1274,7 +1274,8 @@ public abstract class EntityLiving extends Entity {
 
         this.world.methodProfiler.b();
         this.world.methodProfiler.a("looting");
-        if (!this.world.isStatic && this.canPickUpLoot && !this.bb && this.world.getGameRules().getBoolean("mobGriefing")) {
+        // CraftBukkit - Don't run mob pickup code on players
+        if (!this.world.isStatic && !(this instanceof EntityPlayer) && this.canPickUpLoot && !this.bb && this.world.getGameRules().getBoolean("mobGriefing")) {
             List list = this.world.a(EntityItem.class, this.boundingBox.grow(1.0D, 0.0D, 1.0D));
             Iterator iterator = list.iterator();