staging: vboxvideo: select GENERIC_ALLOCATOR

The vboxvideo code uses various gen_pool_* functions, so it needs
lib/genalloc.c to be built. In some configs this is not happening,
so add select GENERIC_ALLOCATOR to the Kconfig file to enforce this.

Note all other Kconfig references to GENERIC_ALLOCATOR also use select.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/vboxvideo/Kconfig

@@ -2,6 +2,7 @@ config DRM_VBOXVIDEO
 	tristate "Virtual Box Graphics Card"
 	depends on DRM && X86 && PCI
 	select DRM_KMS_HELPER
+	select GENERIC_ALLOCATOR
 	help
 	  This is a KMS driver for the virtual Graphics Card used in
 	  Virtual Box virtual machines.