wpa_supplicant: Add option -I for additional config file

This option can be used only for global parameters that is not going
to be changed from settings.

Change-Id: I4f18aa0a8503cf8cc3a847ac9fcc15419291edf0
Signed-off-by: Dmitry Shmidt <dimitrysh@google.com>
Signed-off-by: Iliyan Malchev <malchev@google.com>
diff --git a/wpa_supplicant/config_none.c b/wpa_supplicant/config_none.c
index 589ea36..2aac28f 100644
--- a/wpa_supplicant/config_none.c
+++ b/wpa_supplicant/config_none.c
@@ -17,11 +17,16 @@
 #include "base64.h"
 
 
-struct wpa_config * wpa_config_read(const char *name)
+struct wpa_config * wpa_config_read(const char *name, struct wpa_config *cfgp)
 {
 	struct wpa_config *config;
 
-	config = wpa_config_alloc_empty(NULL, NULL);
+	if (name == NULL)
+		return NULL;
+	if (cfgp)
+		config = cfgp;
+	else
+		config = wpa_config_alloc_empty(NULL, NULL);
 	if (config == NULL)
 		return NULL;
 	/* TODO: fill in configuration data */