添加 target:gb2312 以满足中文兼容性

[ruiyuanlu]

Is your feature request related to a problem? Please describe.

当前的 xmake api 检查 set_encodings 时仅支持 utf-8 对于 gb2312 xmake 做 api 检查时会给出 warning

warning: .\xmake.lua:51: unknown encoding value 'target:gb2312', it may be 'target:utf-8'

出于跨平台兼容性需要，希望代码本身用 utf-8 存储, 在 Linux 上使用 utf-8, 但是在 win 上需要避免中文乱码, gb2312 对应 CodePage 936 所以需要增加 target:gb2312 支持

CodePage 和编码名称的对应关系参考的是：https://learn.microsoft.com/zh-cn/windows/win32/Intl/code-page-identifiers

Describe the solution you'd like

API 检查

在 encodings.lua 添加对 target:gb2312 检查

-- imports
import(".api_checker")

function main(opt)
    opt = opt or {}
    api_checker.check_targets("encodings", table.join(opt, {values = {
        "none", "utf-8", "source:utf-8", "target:utf-8", "target:gb2312"}}))
end

添加 nf_encodings 处理

在 cl.lua 和 gcc.lua 中添加对 gb2312 的处理

local charsets = {
        ["utf-8"] = "utf-8",
        utf8 = "utf-8",
        gb2312 = "gb2312"
    }

Describe alternatives you've considered

NO

Additional context

NO

[Issues-translate-bot]

Bot detected the issue body's language is not English, translate it automatically.

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Title: Add target:gb2312 to meet Chinese compatibility

[waruqi]

再试试，xmake update -s dev

[Issues-translate-bot]

Bot detected the issue body's language is not English, translate it automatically.

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Try again, xmake update -s dev

[ruiyuanlu]

OK，没什么问题，thx

[Issues-translate-bot]

Bot detected the issue body's language is not English, translate it automatically.

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OK, no problem, thx