net: Kconfig: add CONFIG_WGET symbol

Let net/wget.c and net/lwip/wget.c depend on CONFIG_WGET, and
cmd/wget.c depend on CONFIG_CMD_WGET. This way, the wget code
can be used regardless of whether the wget command is available.

Signed-off-by: Adriano Cordova <adrianox@gmail.com>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/net/Kconfig b/net/Kconfig
index 76ab7d9..b4bb68d 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -244,6 +244,15 @@
 	  generated. It will be saved to the appropriate environment variable,
 	  too.
 
+config WGET
+	bool "Enable wget"
+	select PROT_TCP if NET
+	select PROT_TCP_LWIP if NET_LWIP
+	select PROT_DNS_LWIP if NET_LWIP
+	help
+	  Selecting this will enable wget, an interface to send HTTP requests
+	  via the network stack.
+
 config TFTP_BLOCKSIZE
 	int "TFTP block size"
 	default 1468