Fix oobread crash in RAnal.hexagon (tests_64900) ##crash

Reported by giantbranch of NSFOCUS TIANJI Lab

Author: trufae

libr/anal/p/anal_hexagon.c

@@ -10,8 +10,11 @@
 #include "hexagon_anal.h"
 
 static int hexagon_v6_op(RAnal *anal, RAnalOp *op, ut64 addr, const ut8 *buf, int len, RAnalOpMask mask) {
-	HexInsn hi = {0};;
+	HexInsn hi = {0};
 	ut32 data = 0;
+	if (len < 4) {
+		return 0;
+	}
 	data = r_read_le32 (buf);
 	int size = hexagon_disasm_instruction (data, &hi, (ut32) addr);
 	op->size = size;