AK: Remove now-unused OSError class

This has been superseded by the more generally useful AK::Error :^)

AK/OSError.h

@@ -1,39 +0,0 @@
-/*
- * Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
- *
- * SPDX-License-Identifier: BSD-2-Clause
- */
-
-#pragma once
-
-#include <AK/Format.h>
-#include <errno.h>
-#include <string.h>
-
-namespace AK {
-
-class OSError {
-public:
-    explicit OSError(int error)
-        : m_error(error)
-    {
-    }
-
-    int error() const { return m_error; }
-    const char* string() const { return strerror(m_error); }
-
-private:
-    int m_error { 0 };
-};
-
-template<>
-struct Formatter<OSError> : Formatter<StringView> {
-    void format(FormatBuilder& builder, const OSError& value)
-    {
-        Formatter<StringView>::format(builder, value.string());
-    }
-};
-
-}
-
-using AK::OSError;