[libcxxabi] When built with ASan, __cxa_throw calls __asan_handle_no_return

The ASan runtime on many systems intercepts cxa_throw just so it
can call asan_handle_no_return first. Some newer systems such as
Fuchsia don't use interceptors on standard library functions at all,
but instead use sanitizer-instrumented versions of the standard
libraries. When libc++abi is built with ASan, cxa_throw can just
call asan_handle_no_return itself so no interceptor is required.

This is a re-land of r311045, which has become safe after r311869
changed compiler-rt to declare __asan_handle_no_return.

Patch by Roland McGrath

Differential Revision: https://reviews.llvm.org/D37229

llvm-svn: 312606