some warning fixes

common.c

@@ -155,7 +155,7 @@ fail:
 int pin_status(struct blob_buf *bb, char *ip_addr)
 {
 	struct json_object *response, *rv_json;
-	char *rv;
+	const char *rv;
 	int pin_status;
 
 	response = mobile_get_pin_status_zte(ip_addr);

libmobile_zte.c

@@ -14,7 +14,7 @@ static void curl_cleaner(CURLcode *curl);
 static size_t write_func(void *buffer, size_t size, size_t nmemb, void *data);
 static int apn_profile_idx(struct json_object *apn_profiles, char *name);
 static int get_apn_profiles_len(char *ip_addr);
-static char *lexer(char **input, char *delimiter);
+static char *lexer(const char **input, char *delimiter);
 static char *get_query_wrapper(char *ip_addr, char *vars);
 static CURLcode perform_post_request(char *ip_addr, CURL *curl, char *query, struct string *str);
 static CURLcode perform_get_request(char *ip_addr, CURL *curl, char *query, struct string *str);
@@ -159,7 +159,7 @@ fail:
  *		Will alter the input string and allocate memory for the return value!
  *		The caller is responsible for freeing the return value.
  */
-static char *lexer(char **input, char *delimiter)
+static char *lexer(const char **input, char *delimiter)
 {
 	char *token, *substr;
 
@@ -351,7 +351,7 @@ static struct json_object *parse_apn_profiles(struct json_object *apn_profiles)
 	char *field_names[13] = {"profile_name", "apn_name", "mode", "wan_dial", "ppp_auth_mode", "ppp_username", "ppp_passwd", "pdp", "pdpd_select", "pdp_addr", "dns_mode", "prefer_dns_manual", "standby_dns_manual"};
 
 	json_object_object_foreach(apn_profiles, key, val) {
-		char *apn_string = json_object_get_string(val);
+		const char *apn_string = json_object_get_string(val);
 		int i = 0;
 		struct json_object *apn_profile = json_object_new_object();
 		char *field_val;