uclibc: add patch to unbreak sparc non-threaded builds

SPARC non-threaded builds are broken, add patch for uClibc & uClibc-ng to fix
it.

Status: upstream uClibc (so likely -ng will follow suit shortly).

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