AIX simplified agent installer fails on systems with newer curl installed

On AIX systems, we assume that the first curl in the path is the curl that shipped with the system. On AIX, this curl typically does not support the -k flag, but the default behavior is as if -k were specified.

If a customer has a newer version of curl installed that does support -k, at present the simplified agent installer fails with cryptic error messages. The cause is that with a newer curl, -k is required, but the simplified agent installer assumes that only very old versions of curl are used on AIX, and so omits -k.

The simplified agent installer should not fail cryptically when the version of curl found on a system supports the -k flag.