SPIGOT-3407: Set damager for evoker fangs

nms-patches/EntityEvokerFangs.patch

@@ -0,0 +1,12 @@
+--- a/net/minecraft/server/EntityEvokerFangs.java
++++ b/net/minecraft/server/EntityEvokerFangs.java
+@@ -108,7 +108,9 @@
+ 
+         if (entityliving.isAlive() && !entityliving.be() && entityliving != entityliving1) {
+             if (entityliving1 == null) {
++                org.bukkit.craftbukkit.event.CraftEventFactory.entityDamage = this; // CraftBukkit
+                 entityliving.damageEntity(DamageSource.MAGIC, 6.0F);
++                org.bukkit.craftbukkit.event.CraftEventFactory.entityDamage = null; // CraftBukkit
+             } else {
+                 if (entityliving1.r(entityliving)) {
+                     return;

src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java

@@ -520,6 +520,8 @@ public class CraftEventFactory {
                 cause = DamageCause.FALL;
             } else if (source == DamageSource.DRAGON_BREATH) {
                 cause = DamageCause.DRAGON_BREATH;
+            } else if (source == DamageSource.MAGIC) {
+                cause = DamageCause.MAGIC;
             } else {
                 throw new IllegalStateException(String.format("Unhandled damage of %s by %s from %s", entity, damager.getHandle(), source.translationIndex));
             }