MFC r264823 (ed): Make usage printing more consistent with other tools.

- Introduce a separate usage() function.
- Don't use argv[0]. Directly name the application, as we do elsewhere.
- Don't prepend the application name.
- Don't print two newlines.

Also apply the unnecessary semicolon cleanup from r298089

MFC: r290329,r290336
PR: 204230

r290329:

Use meaningful errno for ssize_t overflow in read().
Catch size_t overflow in malloc().

r290336:

Check for (old|new)size + 1 overflows off_t.

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

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

Silence bogus warning when compiling with gcc46:
error: 'pos' may be used uninitialized in this function

Reviewed by: cperciva
Approved by: dim
MFC after: 3 days

Portability fix for non-POSIX operating systems: Open files in binary mode.

PR: bin/106358
Submitted by: techtonik at php dot net

Add bsdiff and bspatch to the base system. These are tools for
constructing and applying binary patches; in particular, they perform
well (in the sense of constructing small patches) for executable code.
Both portsnap (coming to the base system Real Soon Now) and FreeBSD
Update (coming to the base system a bit later) use bspatch.

This is the same code as the bsdiff-4.2 which has been in the ports
tree (misc/bsdiff) for the past year, with the following exceptions:
1. The license is now the traditional 2-clause BSD;
2. Instead of forking and execing bzip2, the code now uses libbz2; and
3. Some minor changes have been made to fit this code into the base
system (adding $FreeBSD$ tags, putting bsdiff and bspatch into separate
directories, etc.)

This code is rather ugly and has lots of style bugs (mostly because I
wrote it before I had ever heard of style(9)). Some day I'll come
back and clean it up.

Discussed on: freebsd-arch
MFC before: 5.5-RELEASE
Tested by: Several million users (earlier version).