Code review comment for ~epics-core/epics-base/+git/make:rpath-origin

This change adds a small python script. I could not find a GNU Make equivalent for os.path.relpath(). So this MR will likely have to wait until someone translates this into perl.

The epicsGetExecDir() implementations for solaris and freebsd have not been tested. As both of these targets use ELF, $ORIGIN should work there. However, I have no plans to tests on either of these targets and will remove these implementations if they are a barrier to acceptance.

Also, to be clear. This is not a change to the default behavior. Unless specifically required with LINKER_USE_RPATH=ORIGIN linking continues to be done with absolute rpath.