linux-user: Add LoongArch generic header files

This includes:
- sockbits.h
- target_errno_defs.h
- target_fcntl.h
- termbits.h
- target_resource.h
- target_structs.h

Signed-off-by: Song Gao <gaosong@loongson.cn>
Signed-off-by: Xiaojuan Yang <yangxiaojuan@loongson.cn>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: WANG Xuerui <git@xen0n.name>
Message-Id: <20220624031049.1716097-2-gaosong@loongson.cn>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

linux-user/loongarch64/sockbits.h

@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (c) 2021 Loongson Technology Corporation Limited
+ */
+
+#ifndef LOONGARCH_TARGET_SOCKBITS_H
+#define LOONGARCH_TARGET_SOCKBITS_H
+
+#include "../generic/sockbits.h"
+
+#endif