libtirpc: fix build failure after non-IPv6 disabled

Adjust patch 0005 to account for the removed optional IPv6 support
patch, since otherwise it won't apply. Fixes:
http://autobuild.buildroot.net/results/0ad/0ad8c9e331190f72280c3a1e3cd8d42728f818de/



Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>