[lldb] Adjust TestModuleCacheSimple for D115951

Now that we are caching the dwarf index as well, we will always have
more than one cache file (when not using accelerator tables). I have
adjusted the test to check for the presence of one _symtab_ index.

lldb/test/API/functionalities/module_cache/simple_exe/TestModuleCacheSimple.py

@@ -26,7 +26,8 @@ def setUp(self):
 
 
     def get_module_cache_files(self, basename):
-        module_file_glob = os.path.join(self.cache_dir, "llvmcache-*%s*" % (basename))
+        module_file_glob = os.path.join(self.cache_dir,
+                "llvmcache-*%s*-symtab-*" % (basename))
         return glob.glob(module_file_glob)
 
     # Doesn't depend on any specific debug information.