Experimental lexer generator: fix build after jinja2 came along.

tools/lexer_generator/code_generator.py

 # Copyright 2013 the V8 project authors. All rights reserved.
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 # modification, are permitted provided that the following conditions are
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 #       from this software without specific prior written permission.
 #
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 from dfa import Dfa
 import jinja2
+import os
+import sys
 
 class CodeGenerator:
 
   def __init__(self, rule_processor, use_mdfa, debug_print = False):
     if use_mdfa:
       dfa = rule_processor.default_automata().minimal_dfa()
     else:
       dfa = rule_processor.default_automata().dfa()
     self.__dfa = dfa
     self.__default_action = rule_processor.default_action
     self.__debug_print = debug_print
 
   def process(self):
 
     start_node_number = self.__dfa.start_state().node_number()
 
     dfa_states = []
     self.__dfa.visit_all_states(lambda state, acc: dfa_states.append(state))
 
     default_action = self.__default_action
     assert(default_action and default_action.match_action())
     default_action = default_action.match_action()
 
+    sys.path.append(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
     template_env = jinja2.Environment(
       loader = jinja2.PackageLoader('lexer_generator', '.'),
       undefined = jinja2.StrictUndefined)
     template = template_env.get_template('code_generator.jinja')
 
     return template.render(
       start_node_number = start_node_number,
       debug_print = self.__debug_print,
       default_action = default_action,
       dfa_states = dfa_states)