[PATCH 0/2] Libsanitizer merge from upstream r253555.

[Maxim Ostapenko <m dot ostapenko at partner dot samsung dot com>]

Hi!

Following recent discussion 
(https://gcc.gnu.org/ml/gcc-patches/2015-11/msg02310.html), I would like 
to merge recent sanitizer library to GCC to make available new useful 
features from upstream in GCC 6:

* The shadow offset for ASan was unified on Aarch64 for 39 and 42 VMAs 
(http://reviews.llvm.org/D13782). This change would not require any new 
code into compiler side.
* Optional ASan recovery functionality was merged to sanitizer library 
(http://reviews.llvm.org/D12318). This feature requires some minimal 
compiler changes that I'll post below.
* LSan was finally fixed and enabled for AArch64 
(http://reviews.llvm.org/rL250898).

The first patch is the library merge itself. I've also applied 3 GCC 
specific patches here (I don't post them separately to avoid polluting 
ChangeLog):

* Patch for SPARC by David S. Miller 
(https://gcc.gnu.org/ml/gcc-patches/2015-10/msg01855.html).
* Disable ODR violation detection 
(https://gcc.gnu.org/ml/gcc-patches/2015-10/msg01856.html).
* Adjust the fix for https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61771 
to extract the last PC from the stack frame if no valid FP is available 
for ARM (https://gcc.gnu.org/ml/gcc-patches/2015-10/msg01857.html).

The second one reflects to corresponding compiler changes. In 
particular, it just enables -fsanitize-recover=address switch and 
migrates two small testcases from upstream.

Regtested and bootstrapped on {x86_64, aarch64}-unknown-linux-gnu and 
arm-linux-gnueabi. Is it OK for mainline?