enforce our JAVA_HOME to avoid potential conflicts with other Java installations by the user;

--- a/lib/Tools/scala	Wed Apr 25 14:24:27 2012 +0200
+++ b/lib/Tools/scala	Wed Apr 25 15:13:03 2012 +0200
@@ -6,8 +6,6 @@
 
 [ -e "$ISABELLE_HOME/Admin/build" ] && { "$ISABELLE_HOME/Admin/build" jars || exit $?; }
 
-export JAVA_HOME="$ISABELLE_JDK_HOME"
-
 CLASSPATH="$(jvmpath "$CLASSPATH")"
 isabelle_scala scala -Dfile.encoding=UTF-8 \
   "-Djava.ext.dirs=$("$ISABELLE_HOME/src/Tools/JVM/java_ext_dirs")" "$@"

--- a/lib/Tools/scalac	Wed Apr 25 14:24:27 2012 +0200
+++ b/lib/Tools/scalac	Wed Apr 25 15:13:03 2012 +0200
@@ -6,8 +6,6 @@
 
 [ -e "$ISABELLE_HOME/Admin/build" ] && { "$ISABELLE_HOME/Admin/build" jars || exit $?; }
 
-export JAVA_HOME="$ISABELLE_JDK_HOME"
-
 CLASSPATH="$(jvmpath "$CLASSPATH")"
 isabelle_scala scalac -Dfile.encoding=UTF-8 \
   "-Djava.ext.dirs=$("$ISABELLE_HOME/src/Tools/JVM/java_ext_dirs")" "$@"

--- a/lib/scripts/getsettings	Wed Apr 25 14:24:27 2012 +0200
+++ b/lib/scripts/getsettings	Wed Apr 25 15:13:03 2012 +0200
@@ -203,6 +203,9 @@
   ML_IDENTIFIER="${ML_SYSTEM}_${ML_PLATFORM}"
 fi
 
+#enforce JAVA_HOME
+export JAVA_HOME="$ISABELLE_JDK_HOME"
+
 ISABELLE_OUTPUT="$ISABELLE_OUTPUT/$ML_IDENTIFIER"
 
 set +o allexport