Fix FreeBSD issues for elfpatch.  First line of "ldd" is the binary name.
Also add default output filename for 'elfpatch' rather than stdout when stdout is a TTY.
Specifically ignore the BSD-induced error
Merge pull request #32 from zachriggle/elfpatch-freebsdfix

Fix FreeBSD issues for elfpatch.  First line of "ldd" is the binary name...