Have run_code_generation only call vpython when needed

scripts/code_generation_hashes/ESSL_static_builtins.json

 {
   "src/compiler/translator/ImmutableString_autogen.cpp":
-    "325dc410635436401990388b73531c11",
+    "e7c9b98db7d7b435f57ff26fc265efb3",
   "src/compiler/translator/ParseContext_autogen.h":
     "58786d2f352ee1a58d529fb7572c86a4",
   "src/compiler/translator/SymbolTable_autogen.cpp":
@@ -12,7 +12,7 @@
   "src/compiler/translator/builtin_variables.json":
     "04f763459cfbd47831bec22299287e82",
   "src/compiler/translator/gen_builtin_symbols.py":
-    "5fca8cb433dcbbd956ec27dc583ccee8",
+    "466747c0158bab9d4792f066b70bf5ed",
   "src/compiler/translator/tree_util/BuiltIn_autogen.h":
     "69268b2f3bda048ba8aaabe60c9b9912",
   "src/tests/compiler_tests/ImmutableString_test_autogen.cpp":

scripts/run_code_generation.py

@@ -38,12 +38,18 @@ def rebase_script_path(script_path, relative_path):
     return os.path.relpath(os.path.join(os.path.dirname(script_path), relative_path), root_dir)
 
 
-def get_executable_name():
-    return 'vpython.bat' if platform.system() == 'Windows' else 'vpython'
+# Check if we need a module from vpython
+def get_executable_name(first_line):
+    if 'vpython' in first_line:
+        return 'vpython.bat' if platform.system() == 'Windows' else 'vpython'
+    return 'python'
 
 
 def grab_from_script(script, param):
-    res = subprocess.check_output([get_executable_name(), script, param]).strip()
+    res = ''
+    f = open(os.path.basename(script), "r")
+    res = subprocess.check_output([get_executable_name(f.readline()), script, param]).strip()
+    f.close()
     if res == '':
         return []
     return [clean_path_slashes(rebase_script_path(script, name)) for name in res.split(',')]
@@ -190,8 +196,12 @@ def main():
                 os.chdir(get_child_script_dirname(script))
 
                 print('Running ' + name + ' code generator')
-                if subprocess.call([get_executable_name(), os.path.basename(script)]) != 0:
+
+                f = open(os.path.basename(script), "r")
+                if subprocess.call([get_executable_name(f.readline()),
+                                    os.path.basename(script)]) != 0:
                     sys.exit(1)
+                f.close()
 
         # Update the hash dictionary.
         all_new_hashes[fname] = new_hashes

src/compiler/translator/gen_builtin_symbols.py

@@ -23,6 +23,7 @@ import json
 import re
 import os
 import sys
+import random
 
 template_immutablestring_cpp = """// GENERATED FILE - DO NOT EDIT.
 // Generated by {script_name} using data from {variable_data_source_name} and
@@ -1248,7 +1249,7 @@ def process_variable_group(parent_condition, group_name, group, builtin_id_decla
 
 
 def main():
-
+    random.seed(0)
     set_working_dir()
 
     parser = argparse.ArgumentParser()