[v3] Fix / clean-up config vs crosses (2/n)

[Paolo Carlini]

Paolo Carlini wrote:
>> My only comment is that AC_TRY_LINK is a bit more accurate than 
>> AC_TRY_COMPILE, so you might want to consider those changes 
>> carefully. I can imagine systems where things might be declared in 
>> headers, but not defined in the corresponding libraries.  For 
>> example, with uClibc, you can configure the library not to include 
>> various things, but I don't think the headers change.  The same thing 
>> is true on VxWorks and quite possibly in other RTOS environments.
> Yeah, now I remember why Joseph introduced AC_TRY_COMPILE_OR_LINK, for 
> some C99 functions...
... and, those C99 tests changed by Richard Sandiford (not Joseph Myers, 
sorry) to use AC_TRY_COMPILE_OR_LINK are run *unconditionally*, not only 
when native! Indeed, that seems the way to go. In case of problems, we 
(the target maintainers, that is ;) can always add a yes / no parameter 
and enable a configure time option...

Paolo.