This one seems to come and go as the optimizer decides how best
to inline some functions.

A recent change seems to have slightly changed the call stack
produced by the gcc optimizer.

This one is needed with the gcc options -fstack-protector-all -O2
That brings the number of suppressions for test 165 to four, and I
suspect I could find another two missing without trying very hard. I'm
beginning to think suppressions isn't the best way to handle these
kinds of cases.

gcc 4.7.2 with -O2 will optimize Curl_connect by inlining some
functions two levels deep, which makes the valgrind suppression
fail to match. The underlying reason for these idna suppressions is
a gcc strlen optimization when compiling libidn; compiling it with
-fno-builtin-strlen makes this suppression unnecessary.

The call stack was modified in 2dc7ad23 so the supressions didn't work
anymore.

When we introduced curl_easy_perform_ev, this got a slightly modified
call trace. Without this, test 165 causes a false positive valgrind
error.

Without this, test 165 triggers a valgrind error when ran with
curl_easy_perform_ev

Remove internal separated behavior of the easy vs multi intercace.
curl_easy_perform() is now using the multi interface itself.

Several minor multi interface quirks and bugs have been fixed in the
process.

Much help with debugging this has been provided by: Yang Tse