x86: add UD0 instruction
diff --git a/MCInst.c b/MCInst.c
index 0a42091..d521845 100644
--- a/MCInst.c
+++ b/MCInst.c
@@ -23,6 +23,7 @@
 	inst->writeback = false;
 	inst->ac_idx = 0;
 	inst->popcode_adjust = 0;
+	inst->assembly[0] = '\0';
 }
 
 void MCInst_clear(MCInst *inst)