Runtime detection of android_set_abort_message.

[eugenis]

Summary

Use runtime detection (with a weak-undef symbol) of
android_set_abort_message availability. Android NDK provides a single
version of the ASan runtime library to be used for any target API
level, which makes compile-time feature detection impossible (the
library itself is built at API level 9).

[srhines]

I think we actually build at level 14 now (or at least that is the plan), but the fix is needed in any case. Thanks for fixing this up.

compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cc

 #endif
 }
 
 void LogMessageOnPrintf(const char *str) {
   if (common_flags()->log_to_syslog && ShouldLogAfterPrintf())
     WriteToSyslog(str);
 }
 
-#if SANITIZER_ANDROID && __ANDROID_API__ >= 21
-extern "C" void android_set_abort_message(const char *msg);
-void SetAbortMessage(const char *str) { android_set_abort_message(str); }
+#if SANITIZER_ANDROID
+extern "C" __attribute__((weak)) void android_set_abort_message(const char *);
+void SetAbortMessage(const char *str) {
+  if (&android_set_abort_message) android_set_abort_message(str);
+}
 #else
 void SetAbortMessage(const char *str) {}
 #endif
 
 #endif // SANITIZER_LINUX
 
 } // namespace __sanitizer
 
 #endif // SANITIZER_FREEBSD || SANITIZER_LINUX

compiler-rt/lib/ubsan_minimal/ubsan_minimal_handlers.cc

if (sz == kMaxCallerPcs) {
       return false;
     }
     caller_pcs[sz].store(caller, std::memory_order_relaxed);
     return true;
   }
 }
 
 #if defined(__ANDROID__)
-extern "C" void android_set_abort_message(const char *msg);
+extern "C" __attribute__((weak)) void android_set_abort_message(const char *);
 static void abort_with_message(const char *msg) {
-#if __ANDROID_API__ >= 21
-  android_set_abort_message(msg);
-#endif
+  if (&android_set_abort_message) android_set_abort_message(msg);
   abort();
 }
 #else
 static void abort_with_message(const char *) { abort(); }
 #endif
 
 #define INTERFACE extern "C" __attribute__((visibility("default")))