unified scala_exit_status and onExit for dist/bin scripts

Author: philwalk

dist/bin/scalac

@@ -131,4 +131,4 @@ eval "\"$JAVACMD\"" \
      "${residual_args[@]}" \
      "${scripting_string-}"
 scala_exit_status=$?
-exit $scala_exit_status
+onExit

dist/bin/scaladoc

@@ -125,7 +125,7 @@ done
 
 classpathArgs
 
-eval exec "\"$JAVACMD\"" \
+eval "\"$JAVACMD\"" \
      ${JAVA_OPTS:-$default_java_opts} \
      "$DEBUG" \
      "${java_args[@]}" \
@@ -134,4 +134,5 @@ eval exec "\"$JAVACMD\"" \
      "${scala_args[@]}" \
      "${residual_args[@]}" \
      "$scripting_string"
-exit $?
+scala_exit_status=$?
+onExit