[SMTChecker] Fix handling of function calls where the function identifier is nested in a tuple.

test/libsolidity/smtCheckerTests/functions/functions_identifier_nested_tuple_1.sol

@@ -0,0 +1,15 @@
+pragma experimental SMTChecker;
+
+contract C {
+	uint x;
+	function f() public {
+		x = 0;
+		((inc))();
+		assert(x == 1); // should hold
+	}
+
+	function inc() internal returns (uint) {
+		require(x < 100);
+		return ++x;
+	}
+}