and CHECK_FUNC_GETADDRINFO_UNFREEABLE_AI_CANONNAME
internal to CHECK_FUNC_GETADDRINFO

section of the code that was odd-looking previously

function returns an addrinfo with an unfreeable ai_canonname member ptr.

can be created before resolving the IPv6 name.  In the context of running
a test, it doesn't make sense to run an IPv6 test when a host is resolvable
but IPv6 isn't usable.  This should fix failures of test 1085 on hosts with
library and DNS support for IPv6 but where actual use of IPv6 has been
administratively disabled.

function returns an addrinfo with an unfreeable ai_addr member ptr.

test #559 tests internal hash create/add/destroy

when allocating/building the fake Curl_addrinfo.

now to minimally exercise some internal hash routines.

  Select ANSI C89 dialect plus GNU extensions, again.

and isn't strictly needed here.

  Select precise floating-point model, otherwise doubles are less than 64-bit wide

icc test adjustment:

  Select c89 dialect

inclusion by the curl tool without colliding with the curl_strequal functions.

  Enable more icc warnings.

  Optimization disabling options used only for icc 9.1

configure is unable of finding out if it has glibc-style or POSIX-style,
trying to ensure that this condition does not go unnoticed.