Util: Allow dfb_gfx_copy_regions_client() with NULL client to use TLS one.
Util: Allow dfb_gfx_copy_regions_client() with NULL client to use TLS one.

Signed-off-by: Denis Oliver Kropp <3fa78fd63dd76ba74a102cf4e1e79303ef9149a1@directfb.org>

jcdubois/DirectFB,dfbdok/DirectFB1,deniskropp/DirectFB,Distrotech/DirectFB,kevleyski/directfb,sklnet/DirectFB,jcdubois/DirectFB,kevleyski/DirectFB-1,deniskropp/DirectFB,kevleyski/directfb,dfbdok/DirectFB1,DirectFB/directfb,djbclark/directfb-core-DirectFB,dfbdok/DirectFB1,djbclark/directfb-core-DirectFB,mtsekm/test,lancebaiyouview/DirectFB,lancebaiyouview/DirectFB,kaostao/directfb,sklnet/DirectFB,kaostao/directfb,kevleyski/directfb,DirectFB/directfb,mtsekm/test,djbclark/directfb-core-DirectFB,kevleyski/DirectFB-1,lancebaiyouview/DirectFB,Distrotech/DirectFB,kevleyski/directfb,DirectFB/directfb,deniskropp/DirectFB,djbclark/directfb-core-DirectFB,kevleyski/DirectFB-1,sklnet/DirectFB,deniskropp/DirectFB,lancebaiyouview/DirectFB,mtsekm/test,kaostao/directfb,kevleyski/DirectFB-1,sklnet/DirectFB,Distrotech/DirectFB,jcdubois/DirectFB