fix warnings about pointer signedness

networking/arp.c

@@ -200,7 +200,7 @@ static void arp_getdevhw(char *ifname, struct sockaddr *sa,
 		}
 		bb_error_msg("device '%s' has HW address %s '%s'",
 					 ifname, xhw->name,
-					 xhw->print((char *) &ifr.ifr_hwaddr.sa_data));
+					 xhw->print((unsigned char *) &ifr.ifr_hwaddr.sa_data));
 	}
 }
 

networking/sendmail.c

@@ -533,7 +533,7 @@ int sendgetmail_main(int argc ATTRIBUTE_UNUSED, char **argv)
 			// so we reuse md5 space instead of xzalloc(16*2+1)
 #define md5_hex ((uint8_t *)&md5)
 //			uint8_t *md5_hex = (uint8_t *)&md5;
-			*bin2hex(md5_hex, s, 16) = '\0';
+			*bin2hex((char *)md5_hex, s, 16) = '\0';
 			// APOP
 			s = xasprintf("%s %s", opt_user, md5_hex);
 #undef md5_hex