Patch #2477: Added from __future__ import unicode_literals

The new PyParser_*Ex() functions are based on Neal's suggestion and initial patch. The new __future__ feature makes all '' and r'' unicode strings. b'' and br'' stay (byte) strings.
diff --git a/Python/import.c b/Python/import.c
index ecbec15..95cd20d 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -818,11 +818,12 @@
 {
 	PyCodeObject *co = NULL;
 	mod_ty mod;
+	PyCompilerFlags flags;
 	PyArena *arena = PyArena_New();
 	if (arena == NULL)
 		return NULL;
 
-	mod = PyParser_ASTFromFile(fp, pathname, Py_file_input, 0, 0, 0, 
+	mod = PyParser_ASTFromFile(fp, pathname, Py_file_input, 0, 0, &flags, 
 				   NULL, arena);
 	if (mod) {
 		co = PyAST_Compile(mod, pathname, NULL, arena);