rtla: use the definition for stdout fd when calling isatty()

Use the STDOUT_FILENO definition when testing whether the standard
output file descriptor refers to a terminal (for better redability).

Link: https://lore.kernel.org/20240813142338.376039-1-ezulian@redhat.com
Signed-off-by: Eder Zulian <ezulian@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Author: efzrh

tools/tracing/rtla/src/osnoise_top.c

@@ -627,7 +627,7 @@ osnoise_top_apply_config(struct osnoise_tool *tool, struct osnoise_top_params *p
 		auto_house_keeping(&params->monitored_cpus);
 	}
 
-	if (isatty(1) && !params->quiet)
+	if (isatty(STDOUT_FILENO) && !params->quiet)
 		params->pretty_output = 1;
 
 	return 0;

tools/tracing/rtla/src/timerlat_top.c

@@ -850,7 +850,7 @@ timerlat_top_apply_config(struct osnoise_tool *top, struct timerlat_top_params *
 		}
 	}
 
-	if (isatty(1) && !params->quiet)
+	if (isatty(STDOUT_FILENO) && !params->quiet)
 		params->pretty_output = 1;
 
 	return 0;