chaps: do not build pam_helper_mock

This relies on pam headers being present and we do not use
it anyway right now.

BUG=chromium:339404
TEST=cros_workon_make --test platform2 no longer fails with pam headers
     in the buildroot.
Change-Id: Ibd12f79ee1d0c241c8544925ccfae10be47017c9
Reviewed-on: https://chromium-review.googlesource.com/185285
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Darren Krahn <dkrahn@chromium.org>
Commit-Queue: Gaurav Shah <gauravsh@chromium.org>
Tested-by: Gaurav Shah <gauravsh@chromium.org>
diff --git a/chaps.gyp b/chaps.gyp
index e2f0390..9ebbeda 100644
--- a/chaps.gyp
+++ b/chaps.gyp
@@ -160,7 +160,6 @@
             'object_policy_mock.cc',
             'object_pool_mock.cc',
             'object_store_mock.cc',
-            'pam_helper_mock.cc',
             'session_mock.cc',
             'slot_manager_mock.cc',
             'tpm_utility_mock.cc',