MFC r312105,r312162:

r312105:

Conditionalize libwrap support into inetd based on MK_TCP_WRAPPERS

This will allow inetd to stand by itself without libwrap.

Relnotes: yes

r312162:

Fix up r312105

• Only #include tcpd.h when LIBWRAP is true to avoid header include errors
• Only define whichaf when LIBWRAP is true to avoid -Wunused warning and to avoid issues with structs being defined that should only be defined when tcpd.h is included.

Pointyhat to: ngie