strutil: clarify SkipUntil parameters
strutil: clarify SkipUntil parameters

Since a8ca5d35306a ("strutil: replace SSE4 specialization with libc
call"), SkipUntil does actually take a 'list' of delimiters rather than
a list of ranges. Clarify that by renaming the parameter and all local
instances for it.

Signed-off-by: Matthias Maennich <9bce818340fa3fdb97f10fe3386d272c8064360e@google.com>

google/kati,google/kati,google/kati,google/kati,google/kati