Fix a typo and remove an unneeded Tn macro as highlighted by mandoc -Tlint.

Submitted by:		Mateusz Piotrowski
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D15204

lib/libc/sys/recv.2

@@ -28,7 +28,7 @@
 .\"     @(#)recv.2	8.3 (Berkeley) 2/21/94
 .\" $FreeBSD$
 .\"
-.Dd October 3, 2017
+.Dd May 20, 2018
 .Dt RECV 2
 .Os
 .Sh NAME
@@ -198,9 +198,7 @@ If no data is available,
 .Va errno
 is set to
 .Er EAGAIN .
-This flag is not available in strict
-.Tn ANSI
-or C99 compilation mode.
+This flag is not available in strict ANSI or C99 compilation mode.
 The
 .Dv MSG_WAITFORONE
 flag sets MSG_DONTWAIT after the first message has been received.
@@ -298,7 +296,7 @@ system call uses the
 .Fa mmsghdr
 structure, defined as follows in the
 .In sys/socket.h
-header :
+header:
 .Bd -literal
 struct mmsghdr {
 	struct msghdr	 msg_hdr;	/* message header */