add mhtml files to preclass set

libclamav/scanners.c

@@ -2709,7 +2709,8 @@ static int magic_scandesc(cli_ctx *ctx, cli_file_t type)
                 type == CL_TYPE_HWP3 ||
                 type == CL_TYPE_XML_HWP ||
                 type == CL_TYPE_HWPOLE2 ||
-                type == CL_TYPE_OOXML_HWP) {
+                type == CL_TYPE_OOXML_HWP ||
+                type == CL_TYPE_MHTML) {
                 ctx->properties = json_object_new_object();
                 if (NULL == ctx->properties) {
                     cli_errmsg("magic_scandesc: no memory for json properties object\n");