With programs with very large functions it can be useful to distinguish
the callgraph nodes on more than just function names. So for example if
you have multiple calls to the same function, it ends up being separate
nodes in the chain.

This patch adds a new key field to the callgraph options, that allows
comparing nodes on functions (as today, default) and addresses.

Longer term it would be nice to also handle src lines, but that would
need more changes and address is a reasonable proxy for it today.

I right now reference the global params, as there was no simple way to
register a params pointer.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/n/tip-0uskktybf0e7wrnoi5e9b9it@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>