[SPARK-30994][CORE] Update xerces to 2.12.0

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

Manage up the version of Xerces that Hadoop uses (and potentially user apps) to 2.12.0 to match https://issues.apache.org/jira/browse/HADOOP-16530

### Why are the changes needed?

Picks up bug and security fixes: https://www.xml.com/news/2018-05-apache-xerces-j-2120/

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

Should be no behavior changes.

### How was this patch tested?

Existing tests.

Closes #27746 from srowen/SPARK-30994.

Authored-by: Sean Owen <srowen@gmail.com>
Signed-off-by: Sean Owen <srowen@gmail.com>

dev/deps/spark-deps-hadoop-2.7-hive-1.2

@@ -201,7 +201,7 @@ super-csv/2.2.0//super-csv-2.2.0.jar
 threeten-extra/1.5.0//threeten-extra-1.5.0.jar
 univocity-parsers/2.8.3//univocity-parsers-2.8.3.jar
 xbean-asm7-shaded/4.15//xbean-asm7-shaded-4.15.jar
-xercesImpl/2.9.1//xercesImpl-2.9.1.jar
+xercesImpl/2.12.0//xercesImpl-2.12.0.jar
 xmlenc/0.52//xmlenc-0.52.jar
 xz/1.5//xz-1.5.jar
 zjsonpatch/0.3.0//zjsonpatch-0.3.0.jar

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

@@ -215,7 +215,7 @@ transaction-api/1.1//transaction-api-1.1.jar
 univocity-parsers/2.8.3//univocity-parsers-2.8.3.jar
 velocity/1.5//velocity-1.5.jar
 xbean-asm7-shaded/4.15//xbean-asm7-shaded-4.15.jar
-xercesImpl/2.9.1//xercesImpl-2.9.1.jar
+xercesImpl/2.12.0//xercesImpl-2.12.0.jar
 xmlenc/0.52//xmlenc-0.52.jar
 xz/1.5//xz-1.5.jar
 zjsonpatch/0.3.0//zjsonpatch-0.3.0.jar

pom.xml

@@ -1083,6 +1083,12 @@
           </exclusion>
         </exclusions>
       </dependency>
+      <!-- Managed up to match Hadoop in HADOOP-16530 -->
+      <dependency>
+        <groupId>xerces</groupId>
+        <artifactId>xercesImpl</artifactId>
+        <version>2.12.0</version>
+      </dependency>
       <dependency>
         <groupId>org.apache.avro</groupId>
         <artifactId>avro</artifactId>