Milter-greylist

According to manu@...:
> 
> Here is our alpha6
> 
> ftp://ftp.espci.fr/pub/milter-greylist/milter-greylist-4.0a6.tgz
> MD5 (milter-greylist-4.0a6.tgz) = fb469a3947a6821519a62644a4128\ufffd27
> 
> Changes since alpha5:
>         Avoid GeoIP reporting "--" for broken domain (Bernhard Schneider )
>         Fix run-away string (AIDA Shinra)
>         Check for libbind9 if libbind cannot be found (Fabien Tassin)
>         Document ACL on TLS DN (Fabien Tassin)
>         Avoid spurious exit on DATA stage ACL match for multiple recipients

there's an issue with configure. I've already faced it with libbind, that why
I've initially proposed the patch mentionned above, but it's a more general
issue.

On a new server, I've compiled m-g as I usually do, so on my cmd line,
I used (amongst other things) --with-libcurl=/usr.

Configure stopped there:

checking for pthread_create in -lpthread... no
checking for pthread_create in -lc_r... no
checking for pthread_create in -lpthreads -lpthread... no
Required libpthread not found. Use --with-libpthread

that was unexpected on Debian.
Looking at config.log, I found out this has nothing to do this pthread:

==
configure:5632: checking for pthread_create in -lpthread
configure:5662: i486-linux-gnu-gcc -o conftest -Wall -g -O2 -Wall -I/usr/include -I/usr/include -DUSE_CURL  -Wl,-z,defs -L/usr/lib -Wl,--rpath=/usr/lib -L/usr/lib -Wl,--rpath=/usr/lib conftest.c -lpthread  -lcurl  >&5
/usr/bin/ld: cannot find -lcurl
collect2: ld returned 1 exit status
==

I just don't have libcurl on that box. That's my fault but configure should
behave differently. It's the same thing with other optionnal features.

Instead of providing a patch that moves that libcurl test before the
pthreads tests, I think it's wise to take a step back and think.

With the current model, it could be tricky to find the right order of tests
to have something robust.
We could also change the model a little bit and test the optional features
independently.

What do you think ? which way is preferable ?

/Fabien