Resolver: introduced state field in ngx_resolver_srv_name_t.

It keeps the actual state value of a DNS SRV subrequest
and can be used to report a more detailed log for
failed SRV records.

src/core/ngx_resolver.c

@@ -3006,6 +3006,7 @@ ngx_resolver_srv_names_handler(ngx_resolver_ctx_t *cctx)
     ctx->count--;
 
     srv->ctx = NULL;
+    srv->state = cctx->state;
 
     if (cctx->naddrs) {
 

src/core/ngx_resolver.h

@@ -82,6 +82,7 @@ typedef struct {
     u_short                   port;
 
     ngx_resolver_ctx_t       *ctx;
+    ngx_int_t                 state;
 
     ngx_uint_t                naddrs;
     ngx_addr_t               *addrs;