compute block added

test/circuits/compute.circom

@@ -0,0 +1,17 @@
+template X() {
+    signal input x;
+    signal output y;
+    signal x2;
+    signal x3;
+    var a;
+    compute {
+        a = (x*x*x+6)/x;
+        y <-- a;
+    }
+
+    x2 <== x*x;
+    x3 <== x2*x;
+    x*y === x3+6;
+}
+
+component main = X();