tools lib traceevent: Allow setting an alternative symbol resolver

The perf tools have a symbol resolver that includes solving kernel
symbols using either kallsyms or ELF symtabs, and it also is using
libtraceevent to format the trace events fields, including via
subsystem specific plugins, like the "timer" one.

To solve fields like "timer:hrtimer_start"'s "function", libtraceevent
needs a way to map from its value to a function name and addr.

This patch provides a way for tools that already have symbol resolving
facilities to ask libtraceevent to use it when needing to resolve
kernel symbols.

Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: David Ahern <dsahern@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-fdx1fazols17w5py26ia3bwh@git.kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>