Handle the option, make the saved filenames and paths easier to handle.
Don't print '[Leaving...]' for files we never created and don't exist - or unless
verbose is true.
2018-12-23 Iain Sandoe <iain@sandoe.co.uk>
* collect2.c (main): Parse the output file early so we can make nicer
temp names. Respond to “-save-temps” in the GCC OPTIONS.
(maybe_unlink): Don’t print “[Leaving…”] for files we never created
and don’t exist.