tools/record: rework the event printing

tools/record: rework the event printing

For historical (but not very good) reasons, libinput record printed events
from the first device to the output file (or stdout) and buffered everything
else. On ctrl+c, the other devices' descriptions and the buffered events were
appended to the output file.

This makes the printing code rather complex. Simplify it by giving each device
a separate FILE* - the first device points to the real output file, the others
to a tempfile. On Ctrl+C we just append those tempfiles to the real output
file one-by-one and done.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>