fsm: log caller's source for events and state changes, not fsm.c lines

When looking at log output, it is not interesting to see that a state
transition's petty details are implemented in fsm.c. Rather log the *caller's*
source file and line that caused an event, state change and cascading events.

To that end, introduce LOGPSRC() absorbing the guts of LOGP(), to be able to
explicitly pass the source file and line information.

Prepend an underscore to the function names of osmo_fsm_inst_state_chg(),
osmo_fsm_inst_dispatch() and osmo_fsm_inst_term(), and add file and line
arguments to them. Provide the previous names as macros that insert the
caller's __BASE_FILE__ and __LINE__ constants for the new arguments. Hence no
calling code needs to be changed.

In fsm.c, add LOGPFSMSRC to call LOGPSRC, and add LOGPFSMLSRC, and use them in
above _osmo_fsm_inst_* functions.

In addition, in _osmo_fsm_inst_term(), pass the caller's source file and line
on to nested event dispatches, so showing where a cascade originated from.

Change-Id: Iae72aba7bbf99e19dd584ccabea5867210650dcd
3 files changed