Do the full string in get_{compiled,runtime}_version_info().

Have them start the string with "Compiled" or "Running on", and return
the string when done.

Change-Id: Ic4d290c963621fa0385dc5aab766fd4ad31d3810
Reviewed-on: https://code.wireshark.org/review/6155
Reviewed-by: Guy Harris <guy@alum.mit.edu>