cttyhack: move build system bits into cttyhack.c, no code changes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

include/usage.src.h

@@ -678,17 +678,6 @@ INSERT
      "\n	-S SALT" \
 	) \
 
-#define cttyhack_trivial_usage \
-       "PROG ARGS"
-#define cttyhack_full_usage "\n\n" \
-       "Give PROG a controlling tty if possible." \
-     "\nExample for /etc/inittab (for busybox init):" \
-     "\n	::respawn:/bin/cttyhack /bin/sh" \
-     "\nGiving controlling tty to shell running with PID 1:" \
-     "\n	$ exec cttyhack sh" \
-     "\nStarting interactive shell from boot shell script:" \
-     "\n	setsid cttyhack sh" \
-
 #define cut_trivial_usage \
        "[OPTIONS] [FILE]..."
 #define cut_full_usage "\n\n" \