package/intel-gmmlib: needs threads

threads are mandatory since version 19.1.1 and
https://github.com/intel/gmmlib/commit/9e4aa143fb7e7e87332fcb7c9871040ff4a1a1da
resulting in the following build failure since commit
cd206d9b:

CMake Error at /home/thomas/autobuild/instance-2/output-1/host/share/cmake-3.22/Modules/FindPackageHandleStandardArgs.cmake:230 (message):
  Could NOT find Threads (missing: Threads_FOUND)

Fixes:
 - http://autobuild.buildroot.org/results/c1120932e8c212820b239ee8cd4a057623a73376



Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>