Re: Fix EXEEXT mechanism

[Akim Demaille]

| Changes:
|  - moved AC_COMPILER_(OBJ|EXE)EXT before AC_LANG_COMPILER_WORKS,
|    as the latter requires a correct ac_exeext to function

Good, but then do that for all the languages please.

|  - use AS_IF(AC_TRY_EVAL(ac_link)) instead of AC_LINK_IFELSE
|    in AC_EXEEXT_O, as the latter also requires a correct ac_exeext

It's your change that makes this needed, right?  I'm not feeling good
about weakening the test.  I'd much more prefer having the macros
become more independent from each other, for instance, can't we write
AC_LANG_COMPILER_WORKS so that it does not depend upon the extensions?
For instance it could work with `-o' and use the default output?

Hm, I don't know.  This patch seems good to me, but then I would like
to ask you to include a few AC_BEFORE to make sure we never flip these
guys again.  *And* please, adjust the other languages too.