package/lttng-tools: fix static build

Add patch fixing configure.ac for library detection on static build.

Fixes:
  http://autobuild.buildroot.net/results/0f1/0f1e015a0c5a5ac2beeb5011d31a1e0058a32a0d/



Upstream status: Merged

Signed-off-by: Samuel Martin <s.martin49@gmail.com>
Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>