Merge r226396, r240605

Merge r226396, r240605

Make systat(1) accept fractional number of seconds.
Make old alarm(3)-based code use select(2).

Ability to specify small intervals can be very handy while
debugging traffic microbursts.

Note that locale-aware strtod(3) is used to parse delay which
is slightly different from ping.

Fix whitespace inconsistencies in systat(1).

Approved by:	ed (r226396)

git-svn-id: svn://svn.freebsd.org/base/stable/8@243684 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f