perf annotate: Add --symfs option

If you have --symfs in perf report, then you also need it for perf
annotate.  This allows off-box assembly level analysis of perf.data
samples.

This patch complements:

commit ec5761ea
Author: David Ahern <daahern@cisco.com>
Date:   Thu Dec 9 13:27:07 2010 -0700

    perf symbols: Add symfs option for off-box analysis using specified tree
Acked-by: David Ahern <daahern@cisco.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: David Ahern <daahern@cisco.com>
Link: http://lkml.kernel.org/r/20110729232040.GA21838@quadSigned-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf-annotate.txt

@@ -80,6 +80,9 @@ OPTIONS
 	Interleave source code with assembly code. Enabled by default,
 	disable with --no-source.
 
+--symfs=<directory>::
+        Look for files with symbols relative to this directory.
+
 SEE ALSO
 --------
 linkperf:perf-record[1], linkperf:perf-report[1]

tools/perf/builtin-annotate.c

@@ -267,6 +267,8 @@ static const struct option options[] = {
 	OPT_BOOLEAN('P', "full-paths", &full_paths,
 		    "Don't shorten the displayed pathnames"),
 	OPT_STRING('c', "cpu", &cpu_list, "cpu", "list of cpus to profile"),
+	OPT_STRING(0, "symfs", &symbol_conf.symfs, "directory",
+		   "Look for files with symbols relative to this directory"),
 	OPT_BOOLEAN('0', "source", &symbol_conf.annotate_src,
 		    "Interleave source code with assembly code (default)"),
 	OPT_BOOLEAN('0', "asm-raw", &symbol_conf.annotate_asm_raw,