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/deployments/libts/arm-linux/CMakeLists.txt b/deployments/libts/arm-linux/CMakeLists.txt
index 1c190a8..5416656 100644
--- a/deployments/libts/arm-linux/CMakeLists.txt
+++ b/deployments/libts/arm-linux/CMakeLists.txt
@@ -24,6 +24,13 @@
 set(MM_COMM_BUFFER_SIZE "8*4*1024" CACHE STRING "Size of the MM communicate buffer in bytes")
 
 #-------------------------------------------------------------------------------
+#  For user-specific tracing set to TRACE_LEVEL_NONE and implement:
+#  void trace_puts(const char *str)
+#-------------------------------------------------------------------------------
+
+set(TRACE_PREFIX "LIBTS" CACHE STRING "Trace prefix")
+set(TRACE_LEVEL "TRACE_LEVEL_DEBUG" CACHE STRING "Trace level")
+#-------------------------------------------------------------------------------
 #  Components that are specific to deployment in the arm-linux environment.
 #
 #-------------------------------------------------------------------------------