perf record: Add dummy event during system wide synthesis

perf record: Add dummy event during system wide synthesis

During the processing of /proc during event synthesis new processes may
start. Add a dummy event if /proc is to be processed, to capture mmaps
for starting processes. This reuses the existing logic for
initial-delay.

v3 fixes the attr test of test-record-C0
v2 fixes the dummy event configuration and a branch stack issue.

Suggested-by: Stephane Eranian <[email protected]>
Signed-off-by: Ian Rogers <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Kan Liang <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Link: http://lore.kernel.org/lkml/[email protected]
[ split from a larger patch ]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>