tftp(1): switch default transfer mode to binary

netascii is obsolete and inefficient. It isn't even supported by many
clients. Better to use binary mode by default.

Reviewed by:	cem
Relnotes:	yes
Differential Revision:	https://reviews.freebsd.org/D16869

usr.bin/tftp/main.c

@@ -184,7 +184,7 @@ main(int argc, char *argv[])
 
 	acting_as_client = 1;
 	peer = -1;
-	strcpy(mode, "netascii");
+	strcpy(mode, "octet");
 	signal(SIGINT, intr);
 
 	interactive = isatty(STDIN_FILENO);

usr.bin/tftp/tftp.1

@@ -28,7 +28,7 @@
 .\"     @(#)tftp.1	8.2 (Berkeley) 4/18/94
 .\" $FreeBSD$
 .\"
-.Dd June 22, 2011
+.Dd Aug 22, 2018
 .Dt TFTP 1
 .Os
 .Sh NAME
@@ -151,7 +151,7 @@ may be one of
 or
 .Em binary .
 The default is
-.Em ascii .
+.Em binary .
 .Pp
 .It Cm packetdrop [arg]
 Randomly drop