[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.

Patch by Roland McGrath

Differential Revision: https://reviews.llvm.org/D36599

llvm-svn: 311045