Make ppp use <termios.h>, not <sys/tty.h>.

ppp's physical.c is filled with calls to termios. For some reason, it
includes <sys/tty.h>, not <termios.h>. Even though this works with the
current version of FreeBSD, we'd better follow the standards.

Approved by:	philip (mentor)

usr.sbin/ppp/physical.c

@@ -37,9 +37,9 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <sys/tty.h>	/* TIOCOUTQ */
 #include <sys/uio.h>
 #include <sysexits.h>
+#include <termios.h>
 #include <time.h>
 #include <unistd.h>
 #include <utmp.h>