Mitsutoshi Aoe authored Jul 26, 2018 and Ben Gamari committed Jul 30, 2018

Without this change RTS typically doesn't flush some important
events until the process terminates or it doesn't write them at
all in case it terminates abnormally.

Here is a list of such events:

* EVENT_WALL_CLOCK_TIME
* EVENT_OS_PROCESS_PID
* EVENT_OS_PROCESS_PPID
* EVENT_RTS_IDENTIFIER
* EVENT_PROGRAM_ARGS
* EVENT_PROGRAM_ENV

(cherry picked from commit 7a3e1b25)