udhcpc: add -o "do not request options by default" switch
(by L. Gabriel Somlo <somlo AT cmu.edu>)

function                                             old     new   delta
udhcpc_main                                         2513    2554     +41
static.udhcpc_longopts                               226     247     +21
add_param_req_option                                 119     132     +13
packed_usage                                       23952   23964     +12
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 4/0 up/down: 87/0)               Total: 87 bytes

diff --git a/networking/udhcp/files.c b/networking/udhcp/files.c
index 6a93bd0..043a95b 100644
--- a/networking/udhcp/files.c
+++ b/networking/udhcp/files.c
@@ -396,6 +396,7 @@
 	close(fp);
 
 	if (server_config.notify_file) {
+// TODO: vfork-based child creation
 		char *cmd = xasprintf("%s %s", server_config.notify_file, server_config.lease_file);
 		system(cmd);
 		free(cmd);
@@ -406,7 +407,7 @@
 void read_leases(const char *file)
 {
 	int fp;
-	unsigned int i = 0;
+	unsigned i;
 	struct dhcpOfferedAddr lease;
 
 	fp = open_or_warn(file, O_RDONLY);
@@ -414,6 +415,7 @@
 		return;
 	}
 
+	i = 0;
 	while (i < server_config.max_leases
 	 && full_read(fp, &lease, sizeof(lease)) == sizeof(lease)
 	) {
@@ -422,7 +424,7 @@
 		if (y >= server_config.start_ip && y <= server_config.end_ip) {
 			lease.expires = ntohl(lease.expires);
 			if (!server_config.remaining)
-				lease.expires -= time(0);
+				lease.expires -= time(NULL);
 			if (!(add_lease(lease.chaddr, lease.yiaddr, lease.expires))) {
 				bb_error_msg("too many leases while loading %s", file);
 				break;