udhcp: many small fixes:
* arpping(): smaller and even probably fixed
* lots of variables/params converted: ulong -> uint32_t
* uptime() nuked in favor of monotonic_sec()
* udhcp_get_packet(): only one "bad vendor", simplify

function                                             old     new   delta
reservedIp                                            36      35      -1
udhcpc_main                                         2462    2460      -2
addStaticLease                                        64      62      -2
static.broken_vendors                                 16       -     -16
uptime                                                19       -     -19
udhcpd_main                                         1273    1238     -35
udhcp_get_packet                                     223     184     -39
.rodata                                           144162  144106     -56
arpping                                              690     609     -81
------------------------------------------------------------------------------
(add/remove: 0/2 grow/shrink: 0/7 up/down: 0/-251)           Total: -251 bytes
   text    data     bss     dec     hex filename
 734241    3028   14400  751669   b7835 busybox_old
 734005    3028   14400  751433   b7749 busybox_unstripped

diff --git a/networking/udhcp/common.h b/networking/udhcp/common.h
index 006d580..5887504 100644
--- a/networking/udhcp/common.h
+++ b/networking/udhcp/common.h
@@ -80,14 +80,14 @@
 /* from dhcpd.h */
 #define server_config		udhcp_server_config
 
-long uptime(void);
 void udhcp_sp_setup(void);
 int udhcp_sp_fd_set(fd_set *rfds, int extra_fd);
 int udhcp_sp_read(fd_set *rfds);
 int raw_socket(int ifindex);
 int read_interface(const char *interface, int *ifindex, uint32_t *addr, uint8_t *arp);
 int listen_socket(uint32_t ip, int port, const char *inf);
-int arpping(uint32_t yiaddr, uint32_t ip, uint8_t *arp, char *interface);
+/* Returns 1 if no reply received */
+int arpping(uint32_t test_ip, uint32_t from_ip, uint8_t *from_mac, const char *interface);
 
 #if ENABLE_FEATURE_UDHCP_DEBUG
 # define DEBUG(str, args...) bb_info_msg(str, ## args)