coreutils: add gnulib patch to fix librt/libthread link in static case

coreutils was not building in the static link case with uClibc, due to
binaries being linked with librt (for timer functions), but not with
libpthread. However, librt uses functions from libpthread, so both
must be specified. This lack of linking against libpthread was caused
by a deficiency in one of the gnulib m4 macro, for which we add a patch.

Fixes:

  http://autobuild.buildroot.org/results/bd4/bd4cc779b46e3837e3d6c43c97eaf42fdfc3a288/



Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>