[PATCH] LeakSanitizer testsuite

[Yury Gribov]

>> This patch adds initial set of tests and dg infrastructure for
>> LeakSanitizer runtime.
>
> Are you sure we need testsuite for something that doesn't have a GCC code
> generation counterpart at all?

That's a valid point. We want this in GCC because
(1) support for cross-compilation and cross-testing in LLVM LSan is much 
less mature so testing non-Intel platforms there is PITA
(2) even though the code itself is the same, the build scripts and 
compilation options are GCC-specific so it may make sense to test these

As an example of (2), we currently don't have lsan_preinit.o so static 
liblsan isn't fully supported.

We understand that these may or may not be important for other community 
members so will accept either decision.

-Y