In tc-ematch.8, remove no-op .ti requests to prevent translation warnings

These do nothing on an 80-column display. They were clearly somebody's
boilerplate way of setting up hanging indents, but the syntax lines
are way too short to require them. And since most were argumentless
they would have been no-ops on any sized display.
ip-rule.8: Fix presentational use of .SS.
netns: follow return value conventions of the rest of the code

The netns code was using EXIT_SUCCESS/EXIT_FAILURE but the rest of the ip
code used -1 explictly, so change to follow convention. Also, certain types
of errors like fork failure should abort a batch operation, rather than just
returning an error.