RFC: Documenting Linux specific behaviour of --rpath and --rpath-link

[Fangrui Song]

On 2021-04-09, Hans-Peter Nilsson wrote:
>On Wed, 7 Apr 2021, Nick Clifton via Binutils wrote:
>>   [Begin new text]
>>
>>      Note however on Linux based systems there is an additional caveat:
>>      If the '--as-needed' option is active _and_ a shared library is
>>      located which would normally satisfy the search _and_ this library
>>      does not have DT_NEEDED tag for 'libc.so' _and_ there is a shared
>>      library later on in the set of search directories which also
>>      satisfies the search _and_ this second shared library does have a
>>      DT_NEEDED tag for 'libc.so' _then_ the second library will be
>>      selected instead of the first.
>>
>>   [End new text]
>>
>>
>> I thought about trying to add an explanation of why this behaviour is
>> mandated, but I felt that I was getting out of my depth at that point.
>
>Swimming or diving or asking for sufficient assistance is not an
>option?  1/2 :)
>
>> So - does anyone have any comment or corrections for this new text ?
>
>This looks sufficiently weird that someone's insanity is in
>question.  Is it me?  Isn't it actually a bug swept under the
>rug because of "compability"?
>
>brgds, H-P

The long conjunction clauses ... do make it feel like a weird
compatibility workaround which should be dropped somehow..

In gold and ld.lld, -rpath-link is simply ignored.