MFC r282073:

- Fix style(9) a bit
-- Fix whitespace
-- Use err/errx
-- Remove superfluous braces
- Be a bit more defensive with input from the end-user
- Don't throw a floating point exception by dividing by 0 when processing a
zero-byte file

MFC r264400,r265836:

r264400:

NO_MAN= has been deprecated in favor of MAN= for some time, go ahead
and finish the job. ncurses is now the only Makefile in the tree that
uses it since it wasn't a simple mechanical change, and will be
addressed in a future commit.

r265836:

Remove last two NO_MAN= in the tree. In both of these cases, MAN= is
what is needed.

MFC r282073:

- Fix style(9) a bit
-- Fix whitespace
-- Use err/errx
-- Remove superfluous braces
- Be a bit more defensive with input from the end-user
- Don't throw a floating point exception by dividing by 0 when processing a
zero-byte file

MFC r264400,r265836:

r264400:

NO_MAN= has been deprecated in favor of MAN= for some time, go ahead
and finish the job. ncurses is now the only Makefile in the tree that
uses it since it wasn't a simple mechanical change, and will be
addressed in a future commit.

r265836:

Remove last two NO_MAN= in the tree. In both of these cases, MAN= is
what is needed.