[MIPS] Add seccomp bpf support

Add support for seccomp bpf sandboxing on MIPS architecture.
Enable testing of seccomp bpf sandbox.

Support for seccomp bpf for MIPS was added in Linux kernel version 3.15.

This patchset was reviewed in https://chromiumcodereview.appspot.com/260793003/ and re-created
to workaround a commit-queue issue.

BUG=369594
TEST=sandbox_linux_unittests

Review URL: https://codereview.chromium.org/409403003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@285538 0039d316-1c4b-4281-b951-d872f2087c98
25 files changed