lint: add missing strings for operators

It's difficult to keep these lists in sync when they are spread over
several files.  The lists had been inconsistent since 2008-04-26.  The
inconsistency didn't lead to undefined behavior though since the
operator names are only used in 2 places:

1. check_integer_conversion in message 324 only calls that function with
a few selected operators, all of which are above the missing ones.

2. mkinit prints the node including its operator, but only in debug
mode.  Furthermore I'm not sure whether any of the broken operator names
could ever be accessed at this place since mkinit is only called for
expressions, and the node types are INIT, CASE, FARG, which are all
special.

(rillig)