Fix view distance API handling on negative values

Prior to this change, if a player was ever set to have a negative view
distance, an attempt to set them back to the default would fail, leading
to them appearing to be stuck in that state.

Now we just interpret that negative value as a "reset" to default.

Spigot-Server-Patches/Add-player-view-distance-API.patch

@@ -25,7 +25,7 @@ index 9829cdd89..5b0675718 100644
      // CraftBukkit start
      public String displayName;
 diff --git a/src/main/java/net/minecraft/server/PlayerChunkMap.java b/src/main/java/net/minecraft/server/PlayerChunkMap.java
-index e4ed2e991..cfac05750 100644
+index e4ed2e991..9627a9be0 100644
 --- a/src/main/java/net/minecraft/server/PlayerChunkMap.java
 +++ b/src/main/java/net/minecraft/server/PlayerChunkMap.java
 @@ -0,0 +0,0 @@ public class PlayerChunkMap {
@@ -178,17 +178,26 @@ index e4ed2e991..cfac05750 100644
      // CraftBukkit end
 +
 +    // Paper start - Player view distance API
-+    public void updateViewDistance(EntityPlayer player, int toSet) {
++    public void updateViewDistance(EntityPlayer player, int distanceIn) {
 +        final int oldViewDistance = player.getViewDistance();
 +
-+        int viewDistance = MathHelper.clamp(toSet, 3, 32);
-+        if (toSet < 0) {
-+            viewDistance = -1;
++        // This represents the view distance that we will set on the player
++        // It can exist as a negative value
++        int playerViewDistance = MathHelper.clamp(distanceIn, 3, 32);
++
++        // This value is the one we actually use to update the chunk map
++        // We don't ever want this to be a negative
++        int toSet = playerViewDistance;
++
++        if (distanceIn < 0) {
++            playerViewDistance = -1;
++            toSet = world.getPlayerChunkMap().getViewDistance();
 +        }
-+        if (viewDistance != oldViewDistance) {
++
++        if (toSet != oldViewDistance) {
 +            // Order matters
-+            this.setViewDistance(player, viewDistance);
-+            player.setViewDistance(viewDistance);
++            this.setViewDistance(player, toSet);
++            player.setViewDistance(playerViewDistance);
 +        }
 +    }
 +    // Paper end