MFC r300395:

Silence top(1) compiler warnings

The contrib/top code is no longer maintained upstream (last pulled 16 years
ago). The K&R-style followed by the code spews -Wimplicit-int and -Wreturn-type
warnings, amongst others. This silences 131 warnings with as little modification
as possible by adding necessary return types, definitions, headers, and header
guards, and missing header includes.

The 5 warnings that remain are due to undeclared ncurses references. I didn't
include curses.h and term.h because there are several local functions and macros
that conflict with those definitions.

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

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

This commit was generated by cvs2svn to compensate for changes in r24139,
which included commits to RCS files with non-trunk default branches.

This is the long-awaited import of top into the base system (actually,
the src/contrib/top part right now). This tools is simply too system-
dependant to maintain it in the ports collection.