Ensure we save the results of checking for non-existant files.

volatility/framework/automagic/linux_symbol_cache.py

@@ -29,6 +29,8 @@ class LinuxSymbolCache(interfaces.automagic.AutomagicInterface):
                     vollog.log(constants.LOGLEVEL_V,
                                "Removing cached path {} for banner {}: files does not exist".format(path, banner))
                     linuxbanners[banner].remove(path)
+        # Rewrite it in case we found any files that were no logner present
+        cls.save_linux_banners(linuxbanners)
         return linuxbanners
 
     @classmethod