Enable compiler flags to enhance security

From the original included file:

  Setup extra CFLAGS and LDFLAGS which have 'security' benefits. These
  don't work universally, there are recipes which can't use one, the other
  or both so a blacklist is maintained here. The idea would be over
  time to reduce this list to nothing.

It is likely that:
- some packages in the included layers don't compile with these flags
- bad recipes do not obey these flags
- binary drivers might expose issues at runtime

We need to check and extend the blacklist/whitelist or fix the code or recipe.

Change-Id: Ie4b80abd010eab438567923dea85aac23a565d23
Signed-off-by: Jan-Simon Möller <jsmoeller@linuxfoundation.org>