[DeviceDrivers] fix type unknown issue in pipe

BernardXiong · BernardXiong · commit 00c6e81ecc2e · 2017-12-31T23:52:27.000+08:00
diff --git a/components/drivers/src/pipe.c b/components/drivers/src/pipe.c
@@ -24,6 +24,7 @@
  */
 #include <rthw.h>
 #include <rtdevice.h>
+#include <stdint.h>
 
 #if defined(RT_USING_POSIX)
 #include <dfs_file.h>
