unistd.h: Adds some posix supported definitions.

resolve compilation and functional errors caused by posix definitions
check of third-party libraries.

Signed-off-by: zhanghongyu <zhanghongyu@xiaomi.com>

include/unistd.h

@@ -46,8 +46,6 @@
 #undef  _POSIX_SAVED_IDS
 #undef  _POSIX_JOB_CONTROL
 #define _POSIX_MESSAGE_PASSING 1
-#undef  _POSIX_MAPPED_FILES
-#undef  _POSIX_SHARED_MEMORY_OBJECTS
 #define _POSIX_PRIORITY_SCHEDULING 1
 #ifndef CONFIG_DISABLE_POSIX_TIMERS
 #  define _POSIX_TIMERS 1
@@ -67,6 +65,10 @@
 #define _POSIX_REALTIME_SIGNALS _POSIX_VERSION
 #define _POSIX_THREAD_PRIORITY_SCHEDULING _POSIX_VERSION
 #define _POSIX_SEMAPHORES _POSIX_VERSION
+#define _POSIX_SHARED_MEMORY_OBJECTS _POSIX_VERSION
+#define _POSIX_THREAD_PROCESS_SHARED _POSIX_VERSION
+#define _POSIX_MAPPED_FILES _POSIX_VERSION
+#define _POSIX_THREADS _POSIX_VERSION
 
 #ifdef CONFIG_FS_AIO
 #  define _POSIX_ASYNCHRONOUS_IO _POSIX_VERSION
@@ -92,6 +94,9 @@
 #undef  _POSIX_ASYNC_IO
 #undef  _POSIX_PRIO_IO
 
+#define _XOPEN_UNIX 1
+#define _XOPEN_VERSION 700L
+
 /* Constants used with POSIX pathconf().  pathconf() will return -1 and set
  * errno to ENOSYS for most of these.
  */