Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Revert most part of 200420 as requested, as more review and polish is
needed.

Remove unneeded header includes from usr.bin/ except contributed code.

Tested with: make universe

- For variables holding offset values, use off_t rather than
int, long int or u_int32_t. This changes the interface of
all the CRC calculation and output functions from cksum.
- Print variables of type off_t as intmax_t using a cast and %jd.
- Use the standardized uint32_t type instead of u_int32_t.
To have uint32_t defined, include <stdint.h> where necessary.
Style(9):
- Move #include directives where they belong (esp. crc32.c).
- Add empty lines between #include directives of system headers,
standard library headers and local headers.
- Test a pointer value against NULL.
- Put a space after the return keyword.

PR: bin/48424

ANSIify function definitions to avoid a warning.

Consistently use FBSDID

WARNS=2 fixup.
kill 'register' keyword.

Minimal use of .Ar and .Nm.
Add section number to .Xr reference.
Add DIAGNOSTICS section name.
Remove unused #includes.
Be consistant in the parsing of flags and add missing option in usage string.
Add rcsid.

Avoid infinite loop if read() fails consistently.

PR: misc/7926
Submitted by: Sergey Potapov <sp@alkor.ru>

cksum does a 32-bit checksum, so it needs to use u_int32_t variables,
not u_long. With this change, cksum stops core dumping on alpha (not
a good sign!) and actually computes the same values as it does on i386.

-Wall cleanup.

Add canonical 32bit crc as alorithm 3.

PR: 4615
Reviewed by: phk
Submitted by: Mike Meyer <mwm@shiva.the-park.com>