[net] Remove libc select in SAL and AT Socket function

Signed-off-by: chenyong <1521761801@qq.com>

components/net/Kconfig

@@ -1,18 +1,17 @@
 menu "Network"
 
 menu "Socket abstraction layer"
-    
+
 config RT_USING_SAL
     bool "Enable socket abstraction layer"
     select RT_USING_NETDEV
-    select RT_USING_LIBC
     select RT_USING_SYSTEM_WORKQUEUE
     default n
 
     if RT_USING_SAL
 
         if RT_USING_LWIP || AT_USING_SOCKET
-        
+
             menu "protocol stack implement"
 
                 config SAL_USING_LWIP
@@ -24,29 +23,30 @@ config RT_USING_SAL
                     bool "Support AT Commands stack"
                     default y
                     depends on AT_USING_SOCKET
-                    
+
                 config SAL_USING_TLS
                     bool "Support MbedTLS protocol"
                     default y
                     depends on PKG_USING_MBEDTLS
             endmenu
-        
+
         endif
 
         config SAL_USING_POSIX
             bool "Enable BSD socket operated by file system API"
             default n
             select RT_USING_DFS
+            select RT_USING_LIBC
             select RT_USING_POSIX
             help
                 Let BSD socket operated by file system API, such as read/write and involveed in select/poll POSIX APIs.
-                
+
         if !SAL_USING_POSIX
-            
+
             config SAL_SOCKETS_NUM
                 int "the maximum number of sockets"
                 default 16
-       
+
         endif
 
     endif
@@ -68,7 +68,7 @@ config RT_USING_NETDEV
         config NETDEV_USING_PING
             bool "Enable ping features"
             default y
-        
+
         config NETDEV_USING_NETSTAT
             bool "Enable netstat features"
             default y
@@ -76,8 +76,8 @@ config RT_USING_NETDEV
         config NETDEV_USING_AUTO_DEFAULT
             bool "Enable default netdev automatic change features"
             default y
-        
-        config NETDEV_USING_IPV6 
+
+        config NETDEV_USING_IPV6
             bool "Enable IPV6 protocol support"
             default n
 
@@ -94,7 +94,7 @@ config RT_USING_NETDEV
             bool
             help
                 Defined to synchronize the ip6_addr structure state
-            default n 
+            default n
     endif
 
 endmenu
@@ -277,7 +277,7 @@ config RT_USING_LWIP
         config LWIP_NETIF_STATUS_CALLBACK
             int "Enable netif status callback"
             default 1
-        
+
         config LWIP_NETIF_LINK_CALLBACK
             int "Enable netif link status callback"
             default 1
@@ -314,7 +314,7 @@ config RT_USING_LWIP
         config RT_LWIP_USING_HW_CHECKSUM
             bool "Enable hardware checksum"
             default n
-        
+
         config RT_LWIP_USING_PING
             bool "Enable ping features"
             default y

components/net/at/Kconfig

@@ -9,11 +9,11 @@ if RT_USING_AT
     config AT_DEBUG
         bool "Enable debug log output"
         default n
-    
+
     config AT_USING_SERVER
         bool "Enable AT commands server"
         default n
-    
+
     if AT_USING_SERVER
 
         config AT_SERVER_DEVICE
@@ -44,33 +44,32 @@ if RT_USING_AT
         endchoice
 
     endif
-    
+
     config AT_USING_CLIENT
         bool "Enable AT commands client"
         default n
-    
+
     if AT_USING_CLIENT
 
         config AT_CLIENT_NUM_MAX
             int "The maximum number of supported clients"
             default 1
             range 1 65535
-        
+
         config AT_USING_SOCKET
             bool "Enable BSD Socket API support by AT commnads"
-            select RT_USING_LIBC
             select RT_USING_SAL
             default n
-           
+
     endif
 
     if AT_USING_SERVER || AT_USING_CLIENT
-    
+
         config AT_USING_CLI
             bool "Enable CLI(Command-Line Interface) for AT commands"
             default y
             depends on FINSH_USING_MSH
-         
+
        config AT_PRINT_RAW_CMD
             bool "Enable print RAW format AT command communication data"
             default n
@@ -78,7 +77,7 @@ if RT_USING_AT
         config AT_CMD_MAX_LEN
             int "The maximum lenght of AT Commonds buffer"
             default 128
-         
+
     endif
 
     config AT_SW_VERSION_NUM