Ignore jni/ paths in _CheckAddedDepsHaveTargetApprovals presubmit check.

Improve the implementation so it's easy to add other such directories if/when needed.

BUG=none

Review URL: https://codereview.chromium.org/72763002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235179 0039d316-1c4b-4281-b951-d872f2087c98
Remove SECCOMP_BPF_STANDALONE and port the demo target to gyp.

BUG=316486
R=jln@chromium.org, markus@chromium.org

Review URL: https://codereview.chromium.org/67173005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235180 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 235180