[ASAN] Add macro denoting availability of new `__asan_handle_no_return()` function.

[EricWF]

Summary

Libc++abi attempts to use the newly added __asan_handle_no_return() when built under ASAN. Unfortunately older versions of compiler-rt do not provide this symbol, and so libc++abi needs a way to detect if asan_interface.h actually provides the function.

This patch adds the macro SANITIZER_ASAN_INTERFACE_HAS_HANDLE_NO_RETURN which can be used to detect the availability of the new function.

[mclow.lists]

This looks fine to me (along with D37872)

[phosek]

LGTM

[eugenis]

This function was added to the header recently, but it has been provided by ASan runtime library since the beginning. Why not simply declare it in libc++abi?

[EricWF]

In D37871#871325, @eugenis wrote:

This function was added to the header recently, but it has been provided by ASan runtime library since the beginning. Why not simply declare it in libc++abi?

I didn't know that. I'll come up with a separate patch set for that then.

include/sanitizer/asan_interface.h

#endif
   // fake_stack, but the owner thread need to be alive.
   void *__asan_addr_is_in_fake_stack(void *fake_stack, void *addr, void **beg,
                                      void **end);
 
   // Performs cleanup before a [[noreturn]] function.  Must be called
   // before things like _exit and execl to avoid false positives on stack.
   void __asan_handle_no_return(void);
 
+  // Required to allow ASAN versions of libc++abi to build against older
+  // versions of compiler-rt that do not provide this interface.
+# define SANITIZER_ASAN_INTERFACE_HAS_HANDLE_NO_RETURN
+
 #ifdef __cplusplus
 }  // extern "C"
 #endif
 
 #endif  // SANITIZER_ASAN_INTERFACE_H