Disable validation of previous hash unless validateAllDataLayers is true

We may not need to validate this at all now that we have the ability to validate the current layer, but I'll leave it as it could be useful for debugging. It is disabled by default so not an issue.

src/main/java/org/qortal/arbitrary/ArbitraryDataCombiner.java

@@ -5,6 +5,7 @@ import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.qortal.arbitrary.metadata.ArbitraryDataMetadataPatch;
 import org.qortal.repository.DataException;
+import org.qortal.settings.Settings;
 import org.qortal.utils.Base58;
 import org.qortal.utils.FilesystemUtils;
 
@@ -113,7 +114,7 @@ public class ArbitraryDataCombiner {
     }
 
     private void validatePreviousHash() throws IOException {
-        if (!this.shouldValidateHashes) {
+        if (!Settings.getInstance().shouldValidateAllDataLayers()) {
             return;
         }