Expose DNS timeout error to netd

For resolver stats, RCODE_TIMEOUT has been used for catching DNS timeout
error. This change adds the Support for reporting NETD_RESOLV_TIMEOUT to
frameworks.

Also clean up res_data.cpp as these functions are not used.
  - res_init
  - res_mkquery
  - res_query
  - res_send
  - res_search

Bug: 113916551
Test: as follows
    - built and flash netd
    - system/netd/tests/runtests.sh passed
    - silently drop packets by iptables, the return error is correct
Change-Id: I62ba6759b519d42aef62ae5b756a3c1ae3cb00d8
diff --git a/resolv/res_mkquery.cpp b/resolv/res_mkquery.cpp
index 1f2879d..32c413f 100644
--- a/resolv/res_mkquery.cpp
+++ b/resolv/res_mkquery.cpp
@@ -89,8 +89,12 @@
 // Queries will be padded to a multiple of this length when EDNS0 is active.
 constexpr uint16_t kEdns0Padding = 128;
 
-// Defined in res_data.cpp
-extern const char* _res_opcodes[];
+extern const char* const _res_opcodes[] = {
+        "QUERY",  "IQUERY", "CQUERYM", "CQUERYU", /* experimental */
+        "NOTIFY",                                 /* experimental */
+        "UPDATE", "6",      "7",       "8",        "9",       "10",
+        "11",     "12",     "13",      "ZONEINIT", "ZONEREF",
+};
 
 /*
  * Form all types of queries.