buildroot

uclibc: add patch to fix <unistd.h> header

The bump to uClibc-ng 1.0.8 added some changes in <unistd.h> related
to syncfs() that broke the build for packages including this header
file, such as lighttpd. This commit adds a uClibc-ng patch (submitted
upstream) which fixes the issue.

Fixes:

  http://autobuild.buildroot.org/results/6be/6be17a91373708900082958a59df8b7575df69c0/

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Reported-by: Xi-Sheng Luo <lxsjason@gmail.com>