Fix clang's double-promotion warning
Fix clang's double-promotion warning

Casting to gdouble instead to float to avoid the warning and perhaps
increase the precision.

spice-widget-egl.c:573:28: error: implicit conversion increases
floating-point precision: 'float' to 'gdouble' (aka 'double')
    tx = ((float)d->area.x / (float)d->egl.scanout.width);
       ~  ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

spice-widget-egl.c:574:28: error: implicit conversion increases
floating-point precision: 'float' to 'gdouble' (aka 'double')
    ty = ((float)d->area.y / (float)d->egl.scanout.height);
       ~  ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

spice-widget-egl.c:575:32: error: implicit conversion increases
floating-point precision: 'float' to 'gdouble' (aka 'double')
    tw = ((float)d->area.width / (float)d->egl.scanout.width);
       ~  ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

spice-widget-egl.c:576:33: error: implicit conversion increases
floating-point precision: 'float' to 'gdouble' (aka 'double')
    th = ((float)d->area.height / (float)d->egl.scanout.height);
       ~  ~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Victor Toso <39b7599ff73bbf5db531748ba5250f21fa7120ff@redhat.com>
Acked-by: Frediano Ziglio <55d48b080b2e443e395cde84d2c83b135a4ff48e@redhat.com>

flexVDI/spice-gtk,flexVDI/spice-gtk