Work around std.experimental.allocator issues on <2.074.0.
Work around std.experimental.allocator issues on <2.074.0.

Geod24/vibe.d,etcimon/vibe.d,gedaiu/vibe.d,DBankov/vibe.d,etcimon/vibe.d,rejectedsoftware/vibe.d,chalucha/vibe.d