Core: fix missing core_strings.h dependency
Core: fix missing core_strings.h dependency

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