Bare metal greentea support

-Added the baremetal.json on Tests directory to enable bare-metal
 -Conditional enable of greentea metrics

Note:
Run green tea with bare metal
mbed test  -m target -t GCC_ARM -n tests-mbed_platform-transaction  --app-config TESTS/baremetal.json

TESTS/baremetal.json

@@ -0,0 +1,8 @@
+{ 
+    "requires": [ 
+        "bare-metal", 
+        "greentea-client", 
+        "utest", 
+        "unity" 
+    ] 
+}

features/frameworks/greentea-client/source/greentea_metrics.cpp

@@ -20,6 +20,8 @@
 #include "platform/mbed_stats.h"
 #include <stdint.h>
 
+#if defined(MBED_CONF_RTOS_PRESENT) 
+
 #define THREAD_BUF_COUNT    16
 
 typedef struct {
@@ -234,3 +236,4 @@ static uint32_t print_dec(char *buf, uint32_t value)
 }
 
 #endif
+#endif // #if defined(MBED_CONF_RTOS_PRESENT)

features/frameworks/greentea-client/source/greentea_test_env.cpp

@@ -67,7 +67,9 @@ static void greentea_write_string(const char *str);
  *           This function is blocking.
  */
 void _GREENTEA_SETUP_COMMON(const int timeout, const char *host_test_name, char *buffer, size_t size) {
+#if defined(MBED_CONF_RTOS_PRESENT)	
     greentea_metrics_setup();
+#endif
     // Key-value protocol handshake function. Waits for {{__sync;...}} message
     // Sync preamble: "{{__sync;0dad4a9d-59a3-4aec-810d-d5fb09d852c1}}"
     // Example value of sync_uuid == "0dad4a9d-59a3-4aec-810d-d5fb09d852c1"
@@ -486,7 +488,9 @@ static void greentea_notify_completion(const int result) {
     __gcov_flush();
     coverage_report = false;
 #endif
+#if defined(MBED_CONF_RTOS_PRESENT)
     greentea_metrics_report();
+#endif
     greentea_send_kv(GREENTEA_TEST_ENV_END, val);
     greentea_send_kv(GREENTEA_TEST_ENV_EXIT, 0);
 }
@@ -787,4 +791,4 @@ static int HandleKV(char *out_key,
     return 0;
 }
 
-#endif
+#endif