Closes: #943953 Cherry-pick these from upstream: * arm64: vdso32: Fix broken compat vDSO build warnings * arm64: Kconfig: Make CONFIG_COMPAT_VDSO a proper Kconfig option Then update our build config: * debian/bin/gencontrol.py: Optionally define CROSS_COMPILE_COMPAT make variable * Enable COMPAT_VDSO and set $(CROSS_COMPILE_COMPAT) instead of setting CROSS_COMPILE_COMPAT_VDSO