[libc]修复因libc移除sys/errno.h文件导致的报错

components/libc/pthreads/posix_types.h

@@ -19,16 +19,9 @@
 
 #include <sys/types.h>
 #include <sys/time.h>
-
-/* errno for Keil MDK */
-#if defined(__CC_ARM) || defined(__IAR_SYSTEMS_ICC__)
-#include <sys/errno.h>
-#include <sys/unistd.h>
-#else
 #include <unistd.h>
 #include <errno.h>
 #include <fcntl.h>
-#endif
 
 #endif