Move RTX_NO_MULTITHREAD_CLIB from RTX_Config.h to mbed_rtx_conf.h

This is to avoid change to RTX code base.

Author: ccli8

rtos/TARGET_CORTEX/mbed_rtx_conf.h

@@ -70,4 +70,8 @@
 #define OS_IDLE_THREAD_TZ_MOD_ID     1
 #define OS_TIMER_THREAD_TZ_MOD_ID    1
 
+// Don't adopt default multi-thread support for ARM/ARMC6 toolchains from RTX code base.
+// Provide Mbed-specific instead.
+#define RTX_NO_MULTITHREAD_CLIB
+
 #endif /* MBED_RTX_CONF_H */

rtos/TARGET_CORTEX/rtx5/RTX/Config/RTX_Config.h

@@ -404,11 +404,6 @@
 #define OS_THREAD_LIBSPACE_NUM      OS_THREAD_NUM
 #endif
 
-
-// Don't adopt default multi-thread support for ARM/ARMC6 toolchains from RTX code base.
-// Provide Mbed-specific instead.
-#define RTX_NO_MULTITHREAD_CLIB
-
 //------------- <<< end of configuration section >>> ---------------------------
 
 #endif  // RTX_CONFIG_H_