rubble visibility problem when changing perspective

[mimo]

When changing perspective, the rubble visibility is not correctly treated. To reproduce:

• start as player 1, scout the player 2 cc and then come back so that a mirage is created
• change perspective to player 2 and destroy the cc
• go back as player 1: the rubble and the miraged cc are superimposed

[elexis]

Same as #3601, the rubble is visible through the fog of war

[elexis]

In 19782:

Hide rubble in the fog of war except to the owner, so that other players don't see deleted buildings, especially civic center foundations.
Should use a special filter once the AI supports it (#4611), so that decorative rubble can be placed by maps too.

Differential Revision: ​https://code.wildfiregames.com/D635
Reviewed By: fatherbushido
Refs #3601 #3910 #3179