Fix use of non-existing variable in crashlog.py

Summary:
The method find_matching_slice(self) uses uuid_str on one of the paths but the variable does not exist and so this results in a NameError exception if we take that path.

Differential Revision: https://reviews.llvm.org/D57467

llvm-svn: 352772

lldb/examples/python/crashlog.py

@@ -260,7 +260,7 @@ class CrashLog(symbolication.Symbolicator):
             if not self.resolved_path:
                 self.unavailable = True
                 print("error\n    error: unable to locate '%s' with UUID %s"
-                      % (self.path, uuid_str))
+                      % (self.path, self.get_normalized_uuid_string()))
                 return False
 
         def locate_module_and_debug_symbols(self):