resolv: dead code removal

 - hostalias() and res_hostalias(): these were no-ops

 - res_opt(), res_querydomain(), p_option(), p_query(),
   res_isourserver(), res_nisourserver(): had no callers

 - res_ourserver_p(): made local to res_data.cpp

 - res_send_setqhook(): unused, DnsProxyListener sets the qhook directly
   in android_net_context, which is then copied to res_state by
   res_setnetcontext(). We can further simplify it later on.

Test: atest netd_integration_test
Change-Id: I70f72202e5b940986cac67dc99ab9461af882187
diff --git a/resolv/res_state.cpp b/resolv/res_state.cpp
index ca8d424..738637b 100644
--- a/resolv/res_state.cpp
+++ b/resolv/res_state.cpp
@@ -49,7 +49,7 @@
     struct res_static _rstatic[1];
 } _res_thread;
 
-static _res_thread* _res_thread_alloc(void) {
+static _res_thread* res_thread_alloc(void) {
     _res_thread* rt = (_res_thread*) calloc(1, sizeof(*rt));
 
     if (rt) {
@@ -59,7 +59,7 @@
     return rt;
 }
 
-static void _res_static_done(struct res_static* rs) {
+static void res_static_done(struct res_static* rs) {
     /* fortunately, there is nothing to do here, since the
      * points in h_addr_ptrs and host_aliases should all
      * point to 'hostbuf'
@@ -71,12 +71,12 @@
     free(rs->servent.s_aliases);
 }
 
-static void _res_thread_free(void* _rt) {
+static void res_thread_free(void* _rt) {
     _res_thread* rt = (_res_thread*) _rt;
 
     LOG(VERBOSE) << __func__ << ": rt=" << rt << " for thread=" << gettid();
 
-    _res_static_done(rt->_rstatic);
+    res_static_done(rt->_rstatic);
     res_ndestroy(rt->_nres);
     free(rt);
 }
@@ -84,10 +84,10 @@
 static pthread_key_t _res_key;
 
 __attribute__((constructor)) static void __res_key_init() {
-    pthread_key_create(&_res_key, _res_thread_free);
+    pthread_key_create(&_res_key, res_thread_free);
 }
 
-static _res_thread* _res_thread_get(void) {
+static _res_thread* res_thread_get(void) {
     _res_thread* rt = (_res_thread*) pthread_getspecific(_res_key);
     if (rt != NULL) {
         return rt;
@@ -95,7 +95,7 @@
 
     /* It is the first time this function is called in this thread,
      * we need to create a new thread-specific DNS resolver state. */
-    rt = _res_thread_alloc();
+    rt = res_thread_alloc();
     if (rt == NULL) {
         return NULL;
     }
@@ -110,7 +110,7 @@
         /* This should not happen */
         LOG(VERBOSE) << __func__ << ": tid=" << gettid() << " rt=" << rt
                      << ", res_ninit() returned < 0";
-        _res_thread_free(rt);
+        res_thread_free(rt);
         pthread_setspecific(_res_key, NULL);
         return NULL;
     }
@@ -119,41 +119,25 @@
 
 struct __res_state _nres;
 
-#if 0
-struct resolv_cache*
-__get_res_cache(void)
-{
-    _res_thread*  rt = _res_thread_get();
-
-    if (!rt)
-        return NULL;
-
-    if (!rt->_cache) {
-        rt->_cache = _resolv_cache_create();
-    }
-    return rt->_cache;
-}
-#endif
-
 int* __get_h_errno(void) {
-    _res_thread* rt = _res_thread_get();
+    _res_thread* rt = res_thread_get();
     static int panic = NETDB_INTERNAL;
 
     return rt ? &rt->_h_errno : &panic;
 }
 
-res_state __res_get_state(void) {
-    _res_thread* rt = _res_thread_get();
+res_state res_get_state(void) {
+    _res_thread* rt = res_thread_get();
 
     return rt ? rt->_nres : NULL;
 }
 
-void __res_put_state(res_state res __unused) {
+void res_put_state(res_state res __unused) {
     /* nothing to do */
 }
 
-struct res_static* __res_get_static(void) {
-    _res_thread* rt = _res_thread_get();
+res_static* res_get_static(void) {
+    _res_thread* rt = res_thread_get();
 
     return rt ? rt->_rstatic : NULL;
 }