[autotest] Change os.path.join use in common.py to be portable.

All uses of |os.path.join("x", "../..")| have been changed into
|os.path.join("x", "..", "..")|.

TEST=syntax check all common.py files, trybot passes HWTest
BUG=None

Change-Id: Ic05a2e375352eab4447ae5b180da750ccbc1b914
Reviewed-on: https://gerrit.chromium.org/gerrit/40312
Tested-by: Alex Miller <milleral@chromium.org>
Commit-Queue: Scott Zawalski <scottz@chromium.org>
Reviewed-by: Scott Zawalski <scottz@chromium.org>
Commit-Queue: Alex Miller <milleral@chromium.org>
diff --git a/client/deps/ibusclient/common.py b/client/deps/ibusclient/common.py
index ac26b5d..cda7049 100644
--- a/client/deps/ibusclient/common.py
+++ b/client/deps/ibusclient/common.py
@@ -4,7 +4,7 @@
 
 import os, sys
 dirname = os.path.dirname(sys.modules[__name__].__file__)
-client_dir = os.path.abspath(os.path.join(dirname, "../../"))
+client_dir = os.path.abspath(os.path.join(dirname, "..", ".."))
 sys.path.insert(0, client_dir)
 import setup_modules
 sys.path.pop(0)