[libsanitizer] Fix Mac OS X 10.7 bootstrap (PR sanitizer/82824)

[Jakub Jelinek]

On Mon, Dec 18, 2017 at 11:21:35AM +0100, Rainer Orth wrote:
> I've been using the following in my tree.  Still need to try and get
> this upstream.

Please.  If that doesn't work, I think we need to do it in configure,
sanitizer_internal_defs.h seems to be included very early, so there
is no easy header to override say in include/system/ tree.

> Speaking of which, would it be acceptable to do another full
> libsanitizer merge at this point?  My initial Solaris port has landed
> now, and the necessary changes outside of libsanitizer are almost
> exclusively in Solaris-specific files.  I've already gave it a quick try
> and found no regressions on Linux/x86_64.

I'm afraid it is too late, we have way too many breakages on the trunk and
are seriously behind schedule, and sanitizer merges pretty much always
create numerous regressions.

	Jakub