tools lib traceevent: Introduce pevent_filter_strerror()

The pevent_filter_strerror() function is for receiving actual error
message from pevent_errno value.  To do that, add a static buffer to
event_filter for saving internal error message

If a failed function saved other information in the static buffer
returns the information, otherwise returns generic error message.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1386833777-3790-15-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c
index 22566c2..2ce565a 100644
--- a/tools/lib/traceevent/event-parse.c
+++ b/tools/lib/traceevent/event-parse.c
@@ -5230,22 +5230,7 @@
 
 	idx = errnum - __PEVENT_ERRNO__START - 1;
 	msg = pevent_error_str[idx];
-
-	switch (errnum) {
-	case PEVENT_ERRNO__MEM_ALLOC_FAILED:
-	case PEVENT_ERRNO__PARSE_EVENT_FAILED:
-	case PEVENT_ERRNO__READ_ID_FAILED:
-	case PEVENT_ERRNO__READ_FORMAT_FAILED:
-	case PEVENT_ERRNO__READ_PRINT_FAILED:
-	case PEVENT_ERRNO__OLD_FTRACE_ARG_FAILED:
-	case PEVENT_ERRNO__INVALID_ARG_TYPE:
-		snprintf(buf, buflen, "%s", msg);
-		break;
-
-	default:
-		/* cannot reach here */
-		break;
-	}
+	snprintf(buf, buflen, "%s", msg);
 
 	return 0;
 }