[releng] maven: compile against the Java 1.8 libraries

Remove the JDK_HOME settings that were introduced to build against the
Java 1.7 libraries. Now that the minimum requirement is Java 1.8, this
is wrong and prevents use of Java 1.8 features.

Change-Id: I91a194c9449d7810ef02b038907dbbc708e600a5
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

pom.xml

@@ -190,8 +190,6 @@
     <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
     <maven.build.timestamp.format>yyyyMMddHHmm</maven.build.timestamp.format>
     <bundle-manifest>${project.build.directory}/META-INF/MANIFEST.MF</bundle-manifest>
-    <!-- set JDK_HOME to JAVA_HOME path of JDK7 installation in order to compile against JDK 7 class library -->
-    <JDK_HOME>${JAVA_HOME}</JDK_HOME>
 
     <jgit-last-release-version>4.2.0.201601211800-r</jgit-last-release-version>
     <jsch-version>0.1.53</jsch-version>
@@ -265,9 +263,6 @@
             <encoding>UTF-8</encoding>
             <source>1.8</source>
             <target>1.8</target>
-            <compilerArguments>
-              <bootclasspath>${JDK_HOME}${file.separator}jre${file.separator}lib${file.separator}rt.jar${path.separator}${JDK_HOME}${file.separator}jre${file.separator}lib${file.separator}jsse.jar${path.separator}${JDK_HOME}${file.separator}jre${file.separator}lib${file.separator}jce.jar</bootclasspath>
-            </compilerArguments>
           </configuration>
         </plugin>