Curl_is_resolved() function

make sure it set async false even when using ipv6 (made test case 20 fail
before)

build libcurl to use ares for asynch name resolves.

the define accordingly in the hostip.h header to work nicely all over.

way for emacs, and vim users should provide a similar non-polluting style

for a bigger buffer and this is indeed badness for us. Making this work
on both old and new glibc versions require an ugly loop that in its worse
form cause 45 bad loops when using the correct glibc and a non-resolving
host name... :-/

We want a better fix. Badly.

for freeing single dns cache entries

AGGRESIVE_TEST is also defined, as an addition to MALLOCDEBUG. It doesn't
work for multi interface usage and should only be used with careful
consideration.

counter so that the caller needs to decrease that counter when done with
the returned data.

If compiled with MALLOCDEBUG I've added some extra checking that the counter
is decreased before a handle is closed etc.

memory. Avery Fay brought the example code that proved this.

size isn't big enough. For some reason they now return EAGAIN.

Redhat 8 ships with this glibc version.

when it can't lookup the name (at least in some cases) and thus we need
to make an extra check to detect failures.

case a timeout is set. This seems to work. God knows if it is good enough
or what kind of side-effects we introduce here and now.

I'll close my eyes and cross my fingers. Hard.

Bug report #564585.

after we've realloc() the packed hostent struct.

even when the realloc() actually gets a new memory block

used for "exported" globals.

any name resolved data in any curl handle struct. That way, we won't mind
if the cache entries are pruned for the next time we need them. We'll just
resolve them again instead.

This changes the Curl_resolv() proto. It modifies the SessionHandle struct
but perhaps most importantly, it'll make the internals somewhat dependent
on the DNS cache not being disabled as that will cripple operations somewhat.
Especially for persistant connections.

by Daniel.

A Bjrn Reese patch.

This can be optimized a tidbit, but this is a start.