Find libssl on linux using paths of loaded libraries

Find libssl on linux using paths of loaded libraries

The installed path of libssl may include an element describing the
architecture, e.g. x86_64-linux-gnu or i386-linux-gnu.
In most cases, the libraries already loaded (static dependencies of
Qt, such as libc) will include the path where libssl is installed.

Use dl_iterate_phdr to find the paths. This is a linux specific
function, but it does provide "/lib/<arch>" and "/usr/lib/<arch>"
at the point ssl symbols are being resolved when running the
qsslsocket autotest (which has less dependencies than a typical
Qt app).

Task-number: QTBUG-24694
Change-Id: I9af8081f41bb85c2fcff450a2acda5672a7f7518
Reviewed-by: Harald Fernengel <harald.fernengel@nokia.com>