sm-notify: Make use of AI_NUMERICSERV conditional

Gabor Papp reports nfs-utils-1.2.3 doesn't build on his system that
uses glibc-2.2.5:

make[3]: Entering directory
`/home/gzp/src/nfs-utils-1.2.3/utils/statd'
gcc -DHAVE_CONFIG_H -I. -I../../support/include   -D_GNU_SOURCE -Wall
	-Wextra -Wstrict-prototypes  -pipe -g -O2 -MT sm-notify.o -MD
	-MP -MF .deps/sm-notify.Tpo -c -o sm-notify.o sm-notify.c
	sm-notify.c: In function 'smn_bind_address':
sm-notify.c:247: error: 'AI_NUMERICSERV' undeclared (first use in this
function)
sm-notify.c:247: error: (Each undeclared identifier is reported only
once
sm-notify.c:247: error: for each function it appears in.)
make[3]: *** [sm-notify.o] Error 1

According to the getaddrinfo(3) man page, AI_NUMERICSERV is available
only since glibc 2.3.4.  getaddrinfo(3) seems to convert strings
containing a number to the right port value without the use of
AI_NUMERICSERV, so I think we can survive on older glibc's without it.
It will allow admins to specify service names as well as port numbers
on those versions.

There are uses of AI_NUMERICSERV in gssd and in nfs_svc_create().  The
one in nfs_svc_create() is behind HAVE_LIBTIRPC, and the other is a
issue only for those who want to deploy Kerberos -- likely in both
cases, a more modern glibc will be present.  I'm going to leave those
two.

Fix for:

  https://bugzilla.linux-nfs.org/show_bug.cgi?id=195

Reported-by: "Gabor Z. Papp" <gzp@papp.hu>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Steve Dickson <steved@redhat.com>