On AIX we have to use a special syntax for the dlopen() string argument because the shared libraries are packed in multi-architecture archives. We first try to load the system default libXrender which is contained in the 'X11.base.lib' fileset starting with AIX 6.1

If the latter wasn't successful, we also try to load the version under /opt/freeware. This may be downloaded from the "AIX Toolbox for Linux Applications" even for AIX 5.3