[SMTChecker] Fix ICE when inlining function with tuple expression

test/libsolidity/smtCheckerTests/types/tuple_assignment_multiple_calls.sol

@@ -0,0 +1,14 @@
+pragma experimental SMTChecker;
+
+contract C
+{
+	function f(uint x) public pure returns (uint, uint) {
+		return (x, x);
+	}
+
+	function g() public pure {
+		(uint a, uint b) = f(0);
+		(uint c, uint d) = f(0);
+		assert(a == c && b == d);
+	}
+}