since we're not to concerned with compatibility at this point, it is probably
useful to review the current options and their interaction; for instance
long/short options for everything
Per our IRC discussion, I implemented the following:
* ftrace supports -stack option, which enforces stack tracing on each hit (be it
syscall or function call).
* ftrace doesn't recognize -S and -t anymore. Instead, it understands -sys
option, with the meaning similar to -plt and friends. System calls are not
traced by default anymore.
* Manual page has been updated accordingly.
(Implemented in 7cd0b6627235a9e66fe836693d83dc496a5c7a89.)