Committed: framework bits for disabling libsanitizer. RFC on which targets for which to disable it.

[Hans-Peter Nilsson]

> From: Richard Henderson <rth@redhat.com>
> Date: Tue, 13 Nov 2012 21:38:40 +0100

> On 11/13/2012 05:24 AM, Jakub Jelinek wrote:
> > Yes.  And it shouldn't be just based on target CPU, but also based
> > on target OS, I don't think libsanitizer supports anything but linux (glibc
> > + maybe android) right now, with some smaller or bigger tweaks it could
> > support darwin (but see the reports that it doesn't build there right now)
> > or mingw/cygwin? (but there is a PR that it doesn't build there).
> > So IMHO it should be a whitelist of supported targets with *) case
> > adding noconfigdirs="$noconfigdirs target-libsanitizer", rather than
> > blacklist of few unsupported ones.  Can you please prepare a patch?
> 
> See how libatomic and libitm are structured.
> 
> The logic for what targets are supported belongs
> inside the library directory, and not at top-level.

Right.  And, I think it's worth to repeat ;) that IMHO best to
there simply check that -faddress-sanitizer can compile
error-free (i.e. that TARGET_ASAN_SHADOW_OFFSET is defined on
the target).  No target lists needed.

brgds, H-P