perf tools: Add data object to handle perf data file

perf tools: Add data object to handle perf data file

This patch is adding 'struct perf_data_file' object as a placeholder for
all attributes regarding perf.data file handling. Changing
perf_session__new to take it as an argument.

The rest of the functionality will be added later to keep this change
simple enough, because all the places using perf_session are changed
now.

Signed-off-by: Jiri Olsa <[email protected]>
Acked-by: Namhyung Kim <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Corey Ashford <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>