[asan] Fix Win64 test portability issues

The OOM test should really only run on 32-bits, since it's hard to OOM
on x64.

The operator_array_new_with_dtor_left_oob tests need to account for the
larger array cookie on x64 (8 bytes instead of 4).

Use -std=c++14 in use-after-scope-capture.cc to avoid errors in the MSVC
2015 STL on Windows. The default there is C++14 anyway.

llvm-svn: 276332