Enable -Wsign-compare for netd and fix warnings

Test: atest netd_unit_test netd_integration_test resolv_integration_test
Change-Id: I84347de8f3a3ec0dcc8979037b9c265d145a35f7
diff --git a/resolv/include/netd_resolv/resolv.h b/resolv/include/netd_resolv/resolv.h
index f50744c..9989766 100644
--- a/resolv/include/netd_resolv/resolv.h
+++ b/resolv/include/netd_resolv/resolv.h
@@ -91,7 +91,7 @@
 
 struct ExternalPrivateDnsStatus {
     PrivateDnsMode mode;
-    unsigned numServers;
+    int numServers;
     struct PrivateDnsInfo {
         sockaddr_storage ss;
         const char* hostname;
@@ -119,15 +119,14 @@
 
 // Set name servers for a network
 LIBNETD_RESOLV_PUBLIC int resolv_set_nameservers_for_net(unsigned netid, const char** servers,
-                                                         unsigned numservers, const char* domains,
+                                                         int numservers, const char* domains,
                                                          const __res_params* params);
 
 LIBNETD_RESOLV_PUBLIC int resolv_set_private_dns_for_net(unsigned netid, uint32_t mark,
-                                                         const char** servers,
-                                                         const unsigned numServers,
+                                                         const char** servers, int numServers,
                                                          const char* tlsName,
                                                          const uint8_t** fingerprints,
-                                                         const unsigned numFingerprints);
+                                                         int numFingerprints);
 
 LIBNETD_RESOLV_PUBLIC void resolv_delete_private_dns_for_net(unsigned netid);