[SPARK-35489][BUILD] Upgrade ORC to 1.6.8

### What changes were proposed in this pull request?

This PR aims to upgrade ORC to 1.6.8.

### Why are the changes needed?

This will bring the latest bug fixes.
- https://orc.apache.org/news/2021/05/21/ORC-1.6.8/

### Does this PR introduce _any_ user-facing change?

No.

### How was this patch tested?

Pass the existing CIs.

Closes #32635 from dongjoon-hyun/SPARK-35489.

Authored-by: Dongjoon Hyun <dhyun@apple.com>
Signed-off-by: Dongjoon Hyun <dhyun@apple.com>

dev/deps/spark-deps-hadoop-2.7-hive-2.3

@@ -196,9 +196,9 @@ objenesis/2.6//objenesis-2.6.jar
 okhttp/3.12.12//okhttp-3.12.12.jar
 okio/1.14.0//okio-1.14.0.jar
 opencsv/2.3//opencsv-2.3.jar
-orc-core/1.6.7//orc-core-1.6.7.jar
-orc-mapreduce/1.6.7//orc-mapreduce-1.6.7.jar
-orc-shims/1.6.7//orc-shims-1.6.7.jar
+orc-core/1.6.8//orc-core-1.6.8.jar
+orc-mapreduce/1.6.8//orc-mapreduce-1.6.8.jar
+orc-shims/1.6.8//orc-shims-1.6.8.jar
 oro/2.0.8//oro-2.0.8.jar
 osgi-resource-locator/1.0.3//osgi-resource-locator-1.0.3.jar
 paranamer/2.8//paranamer-2.8.jar

dev/deps/spark-deps-hadoop-3.2-hive-2.3

@@ -167,9 +167,9 @@ objenesis/2.6//objenesis-2.6.jar
 okhttp/3.12.12//okhttp-3.12.12.jar
 okio/1.14.0//okio-1.14.0.jar
 opencsv/2.3//opencsv-2.3.jar
-orc-core/1.6.7//orc-core-1.6.7.jar
-orc-mapreduce/1.6.7//orc-mapreduce-1.6.7.jar
-orc-shims/1.6.7//orc-shims-1.6.7.jar
+orc-core/1.6.8//orc-core-1.6.8.jar
+orc-mapreduce/1.6.8//orc-mapreduce-1.6.8.jar
+orc-shims/1.6.8//orc-shims-1.6.8.jar
 oro/2.0.8//oro-2.0.8.jar
 osgi-resource-locator/1.0.3//osgi-resource-locator-1.0.3.jar
 paranamer/2.8//paranamer-2.8.jar

pom.xml

@@ -137,7 +137,7 @@
     <!-- After 10.15.1.3, the minimum required version is JDK9 -->
     <derby.version>10.14.2.0</derby.version>
     <parquet.version>1.12.0</parquet.version>
-    <orc.version>1.6.7</orc.version>
+    <orc.version>1.6.8</orc.version>
     <jetty.version>9.4.40.v20210413</jetty.version>
     <jakartaservlet.version>4.0.3</jakartaservlet.version>
     <chill.version>0.9.5</chill.version>