[SMTChecker] Fix require with message

test/libsolidity/smtCheckerTests/verification_target/simple_assert_with_require_message.sol

@@ -0,0 +1,9 @@
+pragma experimental SMTChecker;
+contract C {
+	function f(uint a) public pure {
+		require(a < 10, "Input number is too large.");
+		assert(a < 20);
+	}
+}
+// ----
+// Warning: (97-125): Assertion checker does not yet support the type of this literal (literal_string "Input number is too large.").