Fix missing parse_open_file method.

gensyscalls.py was failing to execute because of a missing "self"
keyword when calling parse_open_file.

Test: manual test running gensyscalls.py.

Change-Id: I78db2cba704c5ca56a730019e36601a7ccd069f8
diff --git a/libc/tools/gensyscalls.py b/libc/tools/gensyscalls.py
index fa35984..ab7c247 100755
--- a/libc/tools/gensyscalls.py
+++ b/libc/tools/gensyscalls.py
@@ -511,7 +511,7 @@
     def parse_file(self, file_path):
         logging.debug("parse_file: %s" % file_path)
         with open(file_path) as fp:
-            parse_open_file(fp)
+            self.parse_open_file(fp)
 
 
 class State: