libcli/nbt: remove unused system/network.h from libnbt.h

libcli/nbt: remove unused system/network.h from libnbt.h

This is not needed and breaks the build on AIX:

[ 988/3309] Compiling source4/smb_server/smb/reply.c
"../source4/smb_server/smb/reply.c", line 1093.42: 1506-022 (S) "lseek64" is not a member of "union smb_seek".
"../source4/smb_server/smb/reply.c", line 1093.42: 1506-022 (S) "lseek64" is not a member of "union smb_seek".
"../source4/smb_server/smb/reply.c", line 1093.42: 1506-022 (S) "lseek64" is not a member of "union smb_seek".
"../source4/smb_server/smb/reply.c", line 1093.42: 1506-022 (S) "lseek64" is not a member of "union smb_seek".
"../source4/smb_server/smb/reply.c", line 1109.13: 1506-022 (S) "lseek64" is not a member of "union smb_seek".
"../source4/smb_server/smb/reply.c", line 1110.13: 1506-022 (S) "lseek64" is not a member of "union smb_seek".
"../source4/smb_server/smb/reply.c", line 1111.13: 1506-022 (S) "lseek64" is not a member of "union smb_seek".
"../source4/smb_server/smb/reply.c", line 1113.38: 1506-022 (S) "lseek64" is not a member of "union smb_seek".
Waf: Leaving directory `/opt/home/build/build_farm/samba_4_0_test/bin'
Build failed:  -> task failed (err #1):
	{task: cc reply.c -> reply_1.o}

metze

Autobuild-User(master): Stefan Metzmacher <metze@samba.org>
Autobuild-Date(master): Mon Jun 11 10:32:51 CEST 2012 on sn-devel-104