Turns out using win32 instead of shelling out to child processes is a
bit faster:
name old time/op new time/op delta
GetListIncremental-4 278ms ± 2% 0ms ± 7% -99.93% (p=0.000 n=8+10)
name old alloc/op new alloc/op delta
GetListIncremental-4 238kB ± 0% 9kB ± 0% -96.12% (p=0.000 n=10+8)
name old allocs/op new allocs/op delta
GetListIncremental-4 1.19k ± 0% 0.02k ± 0% -98.49% (p=0.000 n=10+10)
Fixes#3876 (sadly)
Change-Id: I1195ac5de21a8a8b3cdace5871d263e81aa27e91
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>