The source project of this merge request has been removed.
meson: drop pthread-stubs on BSDs
Drop pointless dependency poisoning build of every VAAPI and OpenCL driver. NetBSD already disables downstream by overriding PTHREADSTUBS_LIBS.
libdrm doesn't install static libraries since 56b07338, so this mainly affects subprojects. However, any project that bundles likely uses old version and has broken BSD support.