uniform use of ISABELLE_SCALAC_OPTIONS for scalac, notably for -Xmax-classfile-name on encrypted or docker file-systems;

--- a/src/HOL/Library/code_test.ML	Sun Jan 15 15:51:33 2017 +0100
+++ b/src/HOL/Library/code_test.ML	Sun Jan 15 16:30:49 2017 +0100
@@ -551,7 +551,7 @@
       "}\n"
 
     val compile_cmd =
-      "\"$SCALA_HOME/bin/scalac\" -d " ^ File.bash_path path ^
+      "\"$SCALA_HOME/bin/scalac\" $ISABELLE_SCALAC_OPTIONS -d " ^ File.bash_path path ^
       " -classpath " ^ File.bash_path path ^ " " ^
       File.bash_path code_path ^ " " ^ File.bash_path driver_path
 

--- a/src/Tools/Code/code_scala.ML	Sun Jan 15 15:51:33 2017 +0100
+++ b/src/Tools/Code/code_scala.ML	Sun Jan 15 16:30:49 2017 +0100
@@ -465,7 +465,7 @@
       check = { env_var = "SCALA_HOME",
         make_destination = fn p => Path.append p (Path.explode "ROOT.scala"),
         make_command = fn _ =>
-          "env JAVA_OPTS='-Xms128m -Xmx512m -Xss2m' \"$SCALA_HOME/bin/scalac\" ROOT.scala" } })
+          "env JAVA_OPTS='-Xms128m -Xmx512m -Xss2m' \"$SCALA_HOME/bin/scalac\" $ISABELLE_SCALAC_OPTIONS ROOT.scala" } })
   #> Code_Target.set_printings (Type_Constructor ("fun",
     [(target, SOME (2, fn print_typ => fn fxy => fn [ty1, ty2] =>
       brackify_infix (1, R) fxy (