arm: reset IT block before cs_disasm(). this fixes issue #643
diff --git a/cs.c b/cs.c
index 36d5785..2e011ca 100644
--- a/cs.c
+++ b/cs.c
@@ -562,6 +562,9 @@
 
 	handle->errnum = CS_ERR_OK;
 
+	// reset IT block of ARM structure
+	handle->ITBlock.size = 0;
+
 #ifdef CAPSTONE_USE_SYS_DYN_MEM
 	if (count > 0 && count <= INSN_CACHE_SIZE)
 		cache_size = (unsigned int) count;