tools lib traceevent: Use 'const' in variables pointing to const strings

Fixing the build on fedora 14, 32-bit:

  tools/lib/traceevent/event-parse.c: In function ‘find_cmdline’:
  tools/lib/traceevent/event-parse.c:183:3: error: return discards qualifiers from pointer target type
  tools/lib/traceevent/event-parse.c:186:3: error: return discards qualifiers from pointer target type
  tools/lib/traceevent/event-parse.c:195:2: error: return discards qualifiers from pointer target type
  tools/lib/traceevent/event-parse.c: In function ‘process_func_handler’:
  tools/lib/traceevent/event-parse.c:2658:9: error: assignment discards qualifiers from pointer target type
  tools/lib/traceevent/event-parse.c:2660:9: error: assignment discards qualifiers from pointer target type
  tools/lib/traceevent/event-parse.c: In function ‘print_mac_arg’:
  tools/lib/traceevent/event-parse.c:3892:14: error: initialization discards qualifiers from pointer target type
  tools/lib/traceevent/event-parse.c:3906:7: error: assignment discards qualifiers from pointer target type
  tools/lib/traceevent/event-parse.c: In function ‘pevent_print_event’:
  tools/lib/traceevent/event-parse.c:4412:24: error: initialization discards qualifiers from pointer target type

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/n/tip-0k5g8urwu7vwkgbcbt2x05fe@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/lib/traceevent/event-parse.c

@@ -174,7 +174,7 @@ static int cmdline_init(struct pevent *pevent)
 	return 0;
 }
 
-static char *find_cmdline(struct pevent *pevent, int pid)
+static const char *find_cmdline(struct pevent *pevent, int pid)
 {
 	const struct cmdline *comm;
 	struct cmdline key;
@@ -2637,7 +2637,7 @@ process_func_handler(struct event_format *event, struct pevent_function_handler
 	struct print_arg *farg;
 	enum event_type type;
 	char *token;
-	char *test;
+	const char *test;
 	int i;
 
 	arg->type = PRINT_FUNC;
@@ -3889,7 +3889,7 @@ static void print_mac_arg(struct trace_seq *s, int mac, void *data, int size,
 			  struct event_format *event, struct print_arg *arg)
 {
 	unsigned char *buf;
-	char *fmt = "%.2x:%.2x:%.2x:%.2x:%.2x:%.2x";
+	const char *fmt = "%.2x:%.2x:%.2x:%.2x:%.2x:%.2x";
 
 	if (arg->type == PRINT_FUNC) {
 		process_defined_func(s, data, size, event, arg);
@@ -4409,7 +4409,7 @@ void pevent_event_info(struct trace_seq *s, struct event_format *event,
 void pevent_print_event(struct pevent *pevent, struct trace_seq *s,
 			struct pevent_record *record)
 {
-	static char *spaces = "                    "; /* 20 spaces */
+	static const char *spaces = "                    "; /* 20 spaces */
 	struct event_format *event;
 	unsigned long secs;
 	unsigned long usecs;