Fix tracing in libts

Libts deployments did not include posix_trace.c in the build and as
a result setting TRACE_LEVEL to any value above TRACE_LEVEL_NONE
resulted in a build error.

- Add the missing C file to the build to fix this error.
- Make the arm-linux version of libts to implement tracing
the same way as linux-pc.

Change-Id: I1db6117a0e8aa4955de063e7b22618d4a254973f
Signed-off-by: Gabor Toth <gabor.toth2@arm.com>
diff --git a/environments/arm-linux/posix_trace.c b/environments/arm-linux/posix_trace.c
new file mode 100644
index 0000000..f219b6d
--- /dev/null
+++ b/environments/arm-linux/posix_trace.c
@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: BSD-3-Clause
+/*
+ * Copyright (c) 2024, Arm Limited and Contributors. All rights reserved.
+ */
+
+#include <stdio.h>
+
+#include "trace.h"
+
+#if TRACE_LEVEL >= TRACE_LEVEL_ERROR
+
+void trace_puts(const char *str)
+{
+	puts(str);
+}
+
+#endif /* TRACE_LEVEL >= TRACE_LEVEL_ERROR */