[libcxxabi] Use ASan interface header for declaration. NFC

[smeenai]

Summary

This was changed from using the header to using a forward declaration in
rGc4600ccf891c, since older versions of the header didn't declare the
function. At this point, it's been declared for ~3.5 years, and it
should be pretty safe to assume that we can rely on the ASan interface
header to provide a declaration instead of needing to write our own.

libcxxabi/src/cxa_exception.cpp

 #include <exception>        // for std::terminate
 #include <string.h>         // for memset
 #include "cxa_exception.h"
 #include "cxa_handlers.h"
 #include "fallback_malloc.h"
 #include "include/atomic_support.h"
 
 #if __has_feature(address_sanitizer)
-extern "C" void __asan_handle_no_return(void);
+#include <sanitizer/asan_interface.h>
 #endif
 
 // +---------------------------+-----------------------------+---------------+
 // | __cxa_exception           | _Unwind_Exception CLNGC++\0 | thrown object |
 // +---------------------------+-----------------------------+---------------+
 //                                                           ^
 //                                                           |
 //   +-------------------------------------------------------+