[SMTChecker] Fix ICE in inherited state var

test/libsolidity/smtCheckerTests/inheritance/state_variables.sol

@@ -0,0 +1,17 @@
+pragma experimental SMTChecker;
+
+contract Base {
+	uint x;
+	uint z;
+	uint private t;
+}
+
+contract C is Base {
+	function f(uint y) public {
+		require(x < 10);
+		require(y < 100);
+		z = x + y;
+		assert(z < 150);
+	}
+}
+// ----

test/libsolidity/smtCheckerTests/inheritance/state_variables_2.sol

@@ -0,0 +1,21 @@
+pragma experimental SMTChecker;
+
+contract Base1 {
+	uint x;
+	uint private t;
+}
+
+contract Base2 is Base1 {
+	uint z;
+	uint private t;
+}
+
+contract C is Base2 {
+	function f(uint y) public {
+		require(x < 10);
+		require(y < 100);
+		z = x + y;
+		assert(z < 150);
+	}
+}
+// ----

test/libsolidity/smtCheckerTests/inheritance/state_variables_3.sol

@@ -0,0 +1,18 @@
+pragma experimental SMTChecker;
+
+contract Base {
+	uint x;
+	uint private t;
+}
+
+contract C is Base {
+
+	uint private z;
+	function f(uint y) public {
+		require(x < 10);
+		require(y < 100);
+		z = x + y;
+		assert(z < 150);
+	}
+}
+// ----