Move fork() of console to run_getty() and remove startx conf option

New function helpers.c:run_getty() refactored from main(). Used to
start a default console getty.

Removed startx finit.conf option, superseded by service statement,
see examples/finit.conf for a working use case.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

finit.h

@@ -103,7 +103,6 @@ extern int   debug;
 extern int   verbose;
 extern char *sdown;
 extern char *network;
-extern char *startx;
 extern char *hostname;
 extern char *username;