[Rd] Operations with long altrep vectors cause segfaults on Windows

[Hugh Parsonage]

I can only reproduce on Windows, but reliably (both 4.0.0 and 4.0.2):

$> R --vanilla
x <- c(0L, -2e9:2e9)

# > Segmentation fault

Tried to reproduce on Linux but the above worked as expected. Not an
issue merely with the length of the vector; for example, x <-
rep_len(1:10, 1e10) works, though the altrep vector must be long to
reproduce:

x <- c(0L, -1e9:1e9)  #ok

Segmentation faults occur with the following too:

x <- (-2e9:2e9) + 1L