Change --fingerprint to output to stdout

Change --fingerprint to output to stdout

* src/pdumper.c (dump_fingerprint): Add argument OUTPUT, use it
instead of stderr, update all uses.  Don't print colon if LABEL is
empty.
* src/pdumper.h (dump_fingerprint): Adjust.
* src/emacs.c (main): Print fingerprint to stdout, without label.
* Makefile.in (EMACS_PDMP): Adjust.