blackbox: merge patch and fix linkage problem

-Merge the current blackbox-0.70.1-configure.patch to a new one named
blackbox-001-Fix-configure-ac.patch that will patch configure.ac instead
and also will add -lpthreads to LIBS to fix a linkage problem.
-Force autoreconf to generate the new configure script using the new
patched configure.ac file.

Fixes:

   http://autobuild.buildroot.net/results/a97/a979cc079706be2012fb4b6c72894aca636adfb6/



Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>