Freeing the full filename in all cases.

Freeing the full filename in all cases.

There's a bunch of return cases where we don't free the new full filename
which leads to leaks when writing out new files.  One way to reproduce:
$ rm -f foo
$ nano foo
<hit enter>
<ctrl+o to save>
<ctrl+x to exit>
-> memory leak

Patch by Mike Frysinger.

git-svn-id: svn://svn.savannah.gnu.org/nano/trunk/nano@5563 35c25a1d-7b9e-4130-9fde-d3aeb78583b8