- add configure option --enable-ubsan
- add __ubsan helpers (by Julian)
This requires gcc 4.9.2 or later. Not all platforms are supported, though.
With this change and VEX r3099 regression tests pass on amd64
with a valgrind compiled with -fsanitize=undefined.
git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14995