[Swan] another kind of static checker for C/C++ code

[D. Hugh Redelmeier]

<http://www.itworld.com/security/380406/how-your-compiler-may-be-compromising-application-security>

Finds bugs in code that are due to the license that C compilers have due 
to undefined behaviour.

I remember a kernel bug that looked like this:

	x = *p;
	assert(p != NULL);

The C compiler said that the first statement proved that p was not NULL
(because otherwise the behaviour was undefined and ALL bets are off).  So 
it "knew" that the assertion was true and it need not evaluate it.

Compounding this problem was that this was in a kernel-crafted environment 
where 0 actually pointed at real memory.

This WAS a kernel bug but the optimizing gcc made the effect much worse.

This article points to a project that claims to have a checker 
that finds instances of this kind of bug.

We should try it on Libreswan code.