openbsd: malloc_usable_size is unavailable on OpenBSD
openbsd: malloc_usable_size is unavailable on OpenBSD

andrewrk/zig,andrewrk/zig,zig-lang/zig,raulgrell/zig,zig-lang/zig,raulgrell/zig,raulgrell/zig,zig-lang/zig,raulgrell/zig,raulgrell/zig