trace: Add an option to show tgids in trace output

The tgids are tracked along side the saved_cmdlines tracking, and can be
included in trace output by enabling the 'print-tgid' trace option. This is
useful when doing post-processing of the trace data, as it allows events to be
grouped by tgid.

Change-Id: I52ed04c3a8ca7fddbb868b792ce5d21ceb76250e
Signed-off-by: Jamie Gennis <jgennis@google.com>
trace: add non-hierarchical function_graph option

Add the 'funcgraph-flat' option to the function_graph tracer to use the default
trace printing format rather than the hierarchical formatting normally used.

Change-Id: If2900bfb86e6f8f51379f56da4f6fabafa630909
Signed-off-by: Jamie Gennis <jgennis@google.com>
Clean up duplicate functions
Follow-up Google kernel source
kernel/sys.c