修复代码错误

mico-os/include/common.h

@@ -109,11 +109,11 @@ typedef uint8_t         mico_bool_t;
 #endif
 
 #ifndef ssize_t
-typedef int ssize_t;
+#define ssize_t int
 #endif
 
 #ifndef size_t
-typedef unsigned int size_t;
+#define size_t unsigned int
 #endif
 
 // ==== MiCO Timer Typedef ====