[SMTChecker] Fix ICE in CHC internal calls

test/libsolidity/smtCheckerTests/functions/internal_call_inheritance.sol

@@ -0,0 +1,20 @@
+pragma experimental SMTChecker;
+
+contract C {
+	function c() public pure returns (uint) { return 42; }
+}
+
+contract B is C {
+	function b() public pure returns (uint) { return c(); }
+}
+
+contract A is B {
+	uint public x;
+
+	function a() public {
+		x = b();
+		assert(x < 40);
+	}
+}
+// ----
+// Warning: (254-268): Assertion violation happens here

test/libsolidity/smtCheckerTests/functions/internal_call_inheritance_2.sol

@@ -0,0 +1,24 @@
+pragma experimental SMTChecker;
+
+contract C {
+	uint y;
+	function c(uint _y) public returns (uint) {
+		y = _y;
+		return y;
+	}
+}
+
+contract B is C {
+	function b() public returns (uint) { return c(42); }
+}
+
+contract A is B {
+	uint public x;
+
+	function a() public {
+		x = b();
+		assert(x < 40);
+	}
+}
+// ----
+// Warning: (274-288): Assertion violation happens here