perf symbols: Move symbol filtering to event__preprocess_sample()

So that --dsos, --comm, --symbols can bem used in more tools,
like in perf diff:

$ perf record -f find / > /dev/null
$ perf record -f find / > /dev/null
$ perf diff --dsos /lib64/libc-2.10.1.so | head -5
   1        +22392124     /lib64/libc-2.10.1.so   _IO_vfprintf_internal
   2         +6410655     /lib64/libc-2.10.1.so   __GI_memmove
   3    +1   +9192692     /lib64/libc-2.10.1.so   _int_malloc
   4    -1  -15158605     /lib64/libc-2.10.1.so   _int_free
   5           +45669     /lib64/libc-2.10.1.so   _IO_new_file_xsputn
$

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: <1260914682-29652-3-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 d61f350..6015152 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -56,7 +56,8 @@
 	bool		try_vmlinux_path,
 			use_modules,
 			sort_by_name;
-	const char	*vmlinux_name;
+	const char	*vmlinux_name,
+			*field_sep;
 	char            *dso_list_str,
 			*comm_list_str,
 			*sym_list_str,
@@ -79,6 +80,7 @@
 	struct symbol *sym;
 	u64	      addr;
 	char	      level;
+	bool	      filtered;
 };
 
 struct dso {