Implement ability to disable trust-dns in ClientBuilder.

src/blocking/client.rs

@@ -481,6 +481,27 @@ impl ClientBuilder {
         self.with_inner(move |inner| inner.use_preconfigured_tls(tls))
     }
 
+    /// Enables the [trust-dns](trust_dns_resolver) async resolver instead of a default threadpool using `getaddrinfo`.
+    ///
+    /// If the `trust-dns` feature is turned on, the default option is enabled.
+    ///
+    /// # Optional
+    ///
+    /// This requires the optional `trust-dns` feature to be enabled
+    #[cfg(feature = "trust-dns")]
+    pub fn trust_dns(self, enable: bool) -> ClientBuilder {
+        self.with_inner(|inner| inner.trust_dns(enable))
+    }
+
+    /// Disables the trust-dns async resolver.
+    ///
+    /// This method exists even if the optional `trust-dns` feature is not enabled.
+    /// This can be used to ensure a `Client` doesn't use the trust-dns async resolver
+    /// even if another dependency were to enable the optional `trust-dns` feature.
+    pub fn no_trust_dns(self) -> ClientBuilder {
+        self.with_inner(|inner| inner.no_trust_dns())
+    }
+
     // private
 
     fn with_inner<F>(mut self, func: F) -> ClientBuilder