HDFS-13705:The native ISA-L library loading failure should be made warning rather than an error message. Contributed by Shashikant Banerjee.

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/erasurecode/ErasureCodeNative.java

@@ -46,7 +46,7 @@ public final class ErasureCodeNative {
         loadLibrary();
       } catch (Throwable t) {
         problem = "Loading ISA-L failed: " + t.getMessage();
-        LOG.error("Loading ISA-L failed", t);
+        LOG.warn(problem);
       }
       LOADING_FAILURE_REASON = problem;
     }