Fix crash when passing zero to bytes.concat()

test/libsolidity/semanticTests/array/concat/bytes_concat_zero.sol

@@ -0,0 +1,15 @@
+contract C {
+    function f() public returns (bytes memory) {
+        return bytes.concat(0, -0, 0.0, -0.0, 0e10, 0e-10, 0x00, (0));
+    }
+
+    function g() public returns (bytes memory) {
+        return bytes.concat(0, "abc", 0, "abc", 0);
+    }
+}
+// ====
+// compileViaYul: also
+// compileToEwasm: also
+// ----
+// f() -> 0x20, 8, "\0\0\0\0\0\0\0\0"
+// g() -> 0x20, 9, "\0abc\0abc\0"