[sanitizer] Detect an invalid answer in AtosSymbolizer

[kubamracek]

Summary

On OS X, in AtosSymbolizer, if the answer from atos doesn't contain module name, let's bail and return false. There are some cases where this is beneficial, because we'll try DlAddrSymbolizer next (it's next in the symbolizer chain), which might be able to symbolize something that atos couldn't.

compiler-rt/trunk/lib/sanitizer_common/sanitizer_symbolizer_mac.cc

if (IsAtosErrorMessage(trim)) {
     Report("atos returned an error: %s\n", trim);
     InternalFree(trim);
     return false;
   }
 
   const char *rest = trim;
   char *symbol_name;
   rest = ExtractTokenUpToDelimiter(rest, " (in ", &symbol_name);
+  if (rest[0] == '\0') {
+    InternalFree(symbol_name);
+    InternalFree(trim);
+    return false;
+  }
+
   if (internal_strncmp(symbol_name, "0x", 2) != 0)
     *out_name = symbol_name;
   else
     InternalFree(symbol_name);
   rest = ExtractTokenUpToDelimiter(rest, ") ", out_module);
 
   if (rest[0] == '(') {
     if (out_file) {