[Rd] Creating a long list triggers billions of messages

[Hugh Parsonage]

Reprex (not recommended in an interactive session as it is difficult to kill):
x <- vector("list", 2^31)

which triggers (presumably) billions of error messages like
Error: long vectors are not supported yet ../include/Rinlinedfuns.h

I believe the error arises from checking each element of the list (all
2^31 of them) and issuing an error message for each of them regarding
the length of the overall list.