ANDROID: Replace spaces by '_' for some android filesystem tracepoints.

Andoid files frequently have spaces in them, as do cmdline strings.
Replace these spaces with '_', so tools that parse these tracepoints
don't get terribly confused.

Change-Id: I1cbbedf5c803aa6a58d9b8b7836e9125683c49d1
Signed-off-by: Mohan Srinivasan <srmohan@google.com>