perf symbols: Add a long_name_len member to struct dso

Using a two bytes hole we already had and since we also need to
calculate this strlen for fetching the buildids. We'll use it in
'perf top' to auto-adjust the output based on the terminal
width.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1258479655-28662-1-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index 51c5a4a..5ad1019 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -66,6 +66,7 @@
 	u8		 has_build_id:1;
 	unsigned char	 origin;
 	u8		 build_id[BUILD_ID_SIZE];
+	u16		 long_name_len;
 	const char	 *short_name;
 	char	 	 *long_name;
 	char		 name[0];