[SMTChecker] Fix ICE on tuples of one element that actually have tuple type

test/libsolidity/smtCheckerTests/types/tuple_extra_parens_7.sol

@@ -0,0 +1,14 @@
+pragma experimental SMTChecker;
+contract C {
+	function g() internal pure returns (uint, uint) {
+		return (2, 3);
+	}
+	function f() public {
+		(address(1).call(""));
+		(uint x, uint y) = ((g()));
+		assert(x == 2);
+		assert(y == 3);
+	}
+}
+// ----
+// Warning 5084: (142-152): Type conversion is not yet fully supported and might yield false positives.