Fix syntax error in frontend/native.py

Test: ./ninja -d stats --frontend=frontend/native.py
Change-Id: I4ceb53e365aea16f8c09fafa633be14c9ecfcf01
diff --git a/frontend/native.py b/frontend/native.py
index 4862268..b77ed10 100755
--- a/frontend/native.py
+++ b/frontend/native.py
@@ -128,7 +128,7 @@
                 prefix = 'ninja: warning: '
             elif msg.message.level == 2:
                 prefix = 'ninja: error: '
-            else
+            else:
                 prefix = ''
             self.printer.print_line(prefix + msg.message.message, LinePrinter.LINE_FULL)