Remove names from the NAME section which have their own man pages.

This is similar to the changes made in string(3) and memory(3) man pages previously.

The reasin being that, when you do `whatis ffs', an extra entry will be there in
the output for this page, which is confusing and unncessary.

Bump date for changes in the NAME section.

lib/libc/string/strings.3

@@ -1,4 +1,4 @@
-.\" $NetBSD: strings.3,v 1.2 2016/07/14 17:43:48 abhinav Exp $
+.\" $NetBSD: strings.3,v 1.3 2017/06/17 10:48:09 abhinav Exp $
 .\"
 .\" Copyright (c) 2007 The NetBSD Foundation, Inc.
 .\" All rights reserved.
@@ -27,18 +27,11 @@
 .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 .\" POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd February 17, 2007
+.Dd June 17, 2017
 .Dt STRINGS 3
 .Os
 .Sh NAME
-.Nm bcmp ,
-.Nm bcopy ,
-.Nm bzero ,
-.Nm ffs ,
-.Nm index ,
-.Nm rindex ,
-.Nm strcasecmp ,
-.Nm strncasecmp
+.Nm strings
 .Nd string operations
 .Sh LIBRARY
 .Lb libc