PPC: fix ltrace build on PPC32

Add a patch to fix the build on PPC32 platform. That patch has been
submitted upstream.

Fixes:

  http://autobuild.buildroot.org/results/446/4460aac38225289ef58a8693da9ae520ae07a226/



Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>