fix: Support multiline @examplesIf again

[krlmlr]

Fallout from #1582.

Symptoms: https://github.com/r-prof/profile/actions/runs/10209333641/job/28247195516#step:11:73

Error: Error in map(seq_along(tokens), function(i) { : ℹ In index: 7.
Caused by error in `map()` at roxygen2/R/block.R:216:3:
ℹ In index: 5.
Caused by error in `if (str_trim(x$raw) == "") ...`:
! the condition has length > 1

CC @MichaelChirico.

[MichaelChirico]

thank you!

[hadley]

Thanks!