Fix make-fingerprint off-by-one bug

Problem reported by Alex Gramiak in:
https://lists.gnu.org/r/emacs-devel/2019-04/msg00784.html
* lib-src/make-fingerprint.c (main): Fix recently-introduced
off-by-one bug when accessing args after -r.
1 job for master in 53 minutes and 31 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Test
failed #1409
test-all

00:53:31

 
Name Stage Failure
failed
test-all Test
Makefile:313: recipe for target 'check-doit' failed
make[2]: *** [check-doit] Error 1
make[2]: Leaving directory '/builds/emacs/emacs/test'
make[1]: *** [check-expensive] Error 2
Makefile:288: recipe for target 'check-expensive' failed
make[1]: Leaving directory '/builds/emacs/emacs/test'
Makefile:962: recipe for target 'check-expensive' failed
make: *** [check-expensive] Error 2
ERROR: Job failed: exit code 1