operands are invalid at initialisation (#1159)

Found by oss-fuzz
diff --git a/MCInst.c b/MCInst.c
index bdbb82d..d549624 100644
--- a/MCInst.c
+++ b/MCInst.c
@@ -16,6 +16,12 @@
 
 void MCInst_Init(MCInst *inst)
 {
+	int i;
+
+	for (i = 0; i < 48; i++){
+		inst->Operands[i].Kind = kInvalid;
+	}
+	inst->Opcode = 0;
 	inst->OpcodePub = 0;
 	inst->size = 0;
 	inst->has_imm = false;