stdlib: keep leading slash in absolute ustar filename prefixes

[jakobsvenningsson]

The leading slash where previously dropped from absolute ustar filename prefixes:

> TestFileName1 = string:join(lists:duplicate(99, "a"), "").
"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
> TestFileName2 = string:join(lists:duplicate(10, "a"), "").
"aaaaaaaaaa"
> TarTestFileName1 = filename:join("/tmp", TestFileName1).
"/tmp/aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
> TarTestFileName2 = filename:join("/tmp", TestFileName2).
"/tmp/aaaaaaaaaa"
> [ok = file:write_file(TestFileName, "hello, world\n") || TestFileName <- [TarTestFileName1, TarTestFileName2]].
[ok, ok]
> erl_tar:create("/tmp/test.tar", [TarTestFileName1, TarTestFileName2]).
ok
>  erl_tar:table("/tmp/test.tar").
{ok,["tmp/aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
     "/tmp/aaaaaaaaaa"]}

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CT Test Results

    2 files     94 suites   34m 29s ⏱️
2 044 tests 1 996 ✅ 48 💤 0 ❌
2 353 runs  2 303 ✅ 50 💤 0 ❌

Results for commit 0937a06.

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// Erlang/OTP Github Action Bot

[bjorng]

Thanks! I have force-pushed a few modifications of the test case to your branch and added it to our daily builds. If all tests go well it will be included in RC3 of Erlang/OTP 27.

[bjorng]

The test case fails on Windows. After a quick look, it seems that there is a separate bug for Windows, possibly in the filename module, not something wrong with your fix or test case. I will take another look next week after the release of RC3.