Add threat if pawn is protected by another pawn

src/evaluate.cpp

@@ -580,7 +580,7 @@ namespace {
     b |= shift<Up>(b & TRank3BB) & ~pos.pieces();
 
     // Keep only the squares which are relatively safe
-    b &= ~attackedBy[Them][PAWN] & safe;
+    b &= (~attackedBy[Them][PAWN] | attackedBy[Us][PAWN]) & safe;
 
     // Bonus for safe pawn threats on the next move
     b = pawn_attacks_bb<Us>(b) & pos.pieces(Them);