Linux Sandbox: move PPAPI and Renderer policies to their own files.

We also fix lack of explicit inclusion of build/build_config.h in the
GPU policy.

BUG=325535
R=jorgelo@chromium.org
TBR=creis

Review URL: https://codereview.chromium.org/114813003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@240711 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 240711