[PATCH v2 0/6] Libsanitizer merge from upstream r250806 (was r249633).

[Maxim Ostapenko]

Hi,

this is the second attempt to perform libsanitizer merge from upstream. 
In previous patch set ( 
https://gcc.gnu.org/ml/gcc-patches/2015-10/msg01212.html) we have 
revealed an issue with heuristic for old/new style ubsan_data that was 
needed to be fixed upstream + some errors in compiler changes were 
found. I thought that it would me too messy to proceed review in the 
previous thread, so creating the new one.

The first patch is the merge itself. Since the heuristic fix for old/new 
style ubsan_data selection was applied upstream, I'm bumping revision to 
r250806.
Since there aren't significant changes from r249633, I think this should 
be fine.

The second one combines all compiler-related changes and addresses 
Jakub's nits from previous review.

Patches 3, 4 and 5 are applied to library and were preapproved in 
previous review, but I'm attaching them here to form the full patch set.

In patch 6, I'm trying to add a brief instruction how to perform the 
merge. This is just a documentation patch.

Tested and {A, UB}San bootstrapped on x86-linux-gnu, x86_64-linux-gnu 
and aarch64-linux-gnu targets.

Thanks,
-Maxim