Use one libc wrapper copy for sgx and other platforms (#107)

And remove bh_printf macro for other platform header files

core/shared-lib/platform/zephyr/bh_platform.h

@@ -78,8 +78,6 @@ typedef void* (*thread_start_routine_t)(void*);
 #define wa_malloc bh_malloc
 #define wa_free bh_free
 
-#define bh_printf printf
-
 /* Unit test framework is based on C++, where the declaration of
  snprintf is different.  */
 #ifndef __cplusplus