misc-progs: Fix invalid command line argument parsing.

Fixes #10431.
misc-progs: Remove unused functions.
misc-progs: Move network stuff to own header file.
misc-progs: Remove own copy of strlcat.

Add compatibility define that uses strncat.
misc-progs: Sync STRING_SIZE.
misc-progs: Convert to right file encoding.
misc-progs: Re-indent setuid.c.