Mark chunks as saved after saving them

Prevents re-saving them again later.

patches/server/0016-Rewrite-chunk-system.patch

@@ -9000,10 +9000,10 @@ index 0000000000000000000000000000000000000000..396d72c00e47cf1669ae20dc839c1c96
 +}
 diff --git a/src/main/java/io/papermc/paper/chunk/system/scheduling/NewChunkHolder.java b/src/main/java/io/papermc/paper/chunk/system/scheduling/NewChunkHolder.java
 new file mode 100644
-index 0000000000000000000000000000000000000000..f20faaec3f1fe311b3ac989be5a9148e2e3c59ad
+index 0000000000000000000000000000000000000000..4ce6df7082d4f7ed3651e3d57e379f95dd05715e
 --- /dev/null
 +++ b/src/main/java/io/papermc/paper/chunk/system/scheduling/NewChunkHolder.java
-@@ -0,0 +1,2072 @@
+@@ -0,0 +1,2075 @@
 +package io.papermc.paper.chunk.system.scheduling;
 +
 +import ca.spottedleaf.concurrentutil.completable.Completable;
@@ -10845,6 +10845,8 @@ index 0000000000000000000000000000000000000000..f20faaec3f1fe311b3ac989be5a9148e
 +
 +                    task.queue();
 +
++                    chunk.setUnsaved(false);
++
 +                    return true;
 +                } catch (final ThreadDeath death) {
 +                    throw death;
@@ -10863,6 +10865,7 @@ index 0000000000000000000000000000000000000000..f20faaec3f1fe311b3ac989be5a9148e
 +            } else {
 +                RegionFileIOThread.scheduleSave(this.world, this.chunkX, this.chunkZ, save, RegionFileIOThread.RegionFileType.CHUNK_DATA);
 +            }
++            chunk.setUnsaved(false);
 +        } catch (final ThreadDeath death) {
 +            throw death;
 +        } catch (final Throwable thr) {
@@ -12546,7 +12549,7 @@ index c59fca05484c30b28e883f5b5dde0362f294b517..0c6534e64ef023cf613f2c5407c7598c
  
      private ChunkSystem() {
 diff --git a/src/main/java/net/minecraft/server/MCUtil.java b/src/main/java/net/minecraft/server/MCUtil.java
-index b310d51b7fe3e8cef0a450674725969fe1ce78a4..c9e169a6dca4dd8fe6e27a23deb410664a5d4466 100644
+index 9db975e84609956b2206076e30f17a350adb77d6..f99929c0c5652dedf94b7e34ba599cedf5daf508 100644
 --- a/src/main/java/net/minecraft/server/MCUtil.java
 +++ b/src/main/java/net/minecraft/server/MCUtil.java
 @@ -1,15 +1,28 @@