Revert "JAVA_HOME nad tools.jar not needed for Java testing"

This reverts commit 7373b99079.

Seems to be needed for older jdks - needs some more work, as the
classpath used is not correct for jdk9.

Doc/Manual/Doxygen.html

@@ -1714,7 +1714,9 @@ tool, for example:
 
     
 <p>
-Runtime tests in Java are implemented using Javadoc doclets in tools.jar in the JDK.
+Runtime tests in Java are implemented using Javadoc doclets. To make that work, you
+should have tools.jar from the JDK in your classpath. Or you should have JAVA_HOME
+environment variable defined and pointing to the JDK location.
 </p>
 <p>
 The Java's comment parsing code (the testing part) is located in commentParser.java.

Examples/test-suite/java/Makefile.in

@@ -6,8 +6,10 @@ LANGUAGE     = java
 JAVA         = @JAVA@
 JAVAC        = @JAVAC@
 JAVAFLAGS    = @JAVAFLAGS@
+JAVA_CLASSPATH_SEP = @JAVA_CLASSPATH_SEP@
 SCRIPTSUFFIX = _runme.java
-JAVA_CLASSPATH = .
+
+JAVA_HOME ?= @JAVA_HOME@
 
 srcdir       = @srcdir@
 top_srcdir   = ../@top_srcdir@
@@ -108,6 +110,8 @@ CommentParser.class:
 	echo "Compiling $(srcdir)/CommentParser.java"
 	$(COMPILETOOL) $(JAVAC) -classpath $(JAVA_CLASSPATH) -d . $(srcdir)/CommentParser.java
 
+JAVA_CLASSPATH := .
+$(DOXYGEN_TEST_CASES:=.cpptest): JAVA_CLASSPATH := "$(JAVA_HOME)/lib/tools.jar$(JAVA_CLASSPATH_SEP)."
 $(DOXYGEN_TEST_CASES:=.cpptest): CommentParser.class
 
 # Compiles java files then runs the testcase. A testcase is only run if