coova-chilli: fix "struct sysinfo" redeclaration with recent uClibc.

Patch from http://lists.coova.org/pipermail/chilli/2013-August/002347.html -
refreshed and compile tested locally.

git-svn-id: svn://svn.openwrt.org/openwrt/packages@38058 3c298f89-4303-0410-b956-a3cf2f4a3e73