mingw configure failure detection

Bruce Momjian wrote:

>Andrew Dunstan wrote:
>
>
>>>It's different because we know why we need that one: we understand the
>>>cause of the behavior and we therefore can have some confidence that the
>>>kluge will fix it (or not, as the case may be). I have zero confidence
>>>in looping five times around an "ln" call.
>>>
>>>
>>>
>>>
>>>
>>Even if we don't do that can we *please* put in something that detects
>>the error, and tells the user what they will have to do to fix it?
>>Failing in a situation which we know we can detect and not telling the
>>user is intolerable, IMNSHO.
>>
>>
>
>Agreed. At a minium we have to throw an error and tell them to run it
>again.
>
>

This patch for configure.in detects the link failures in MINGW that I
and others have seen and warns the user they have to fix it up.

cheers

andrew