[LibWebRTC] Build fix for Linux after 276556@main

build://bugs.webkit.org/show_bug.cgi?id=271368

Reviewed by Youenn Fablet.

Implementation of function 'hasRegisteredName' was guarded by
ENABLE_MDNS flag, but definition was not.

* Source/WebKit/NetworkProcess/webrtc/NetworkMDNSRegister.cpp:
(WebKit::NetworkMDNSRegister::hasRegisteredName const):

Canonical link: https://commits.webkit.org/276623@main

Source/WebKit/NetworkProcess/webrtc/NetworkMDNSRegister.cpp

@@ -47,6 +47,11 @@ NetworkMDNSRegister::NetworkMDNSRegister(NetworkConnectionToWebProcess& connecti
 
 NetworkMDNSRegister::~NetworkMDNSRegister() = default;
 
+bool NetworkMDNSRegister::hasRegisteredName(const String& name) const
+{
+    return m_registeredNames.contains(name);
+}
+
 #if ENABLE_MDNS
 struct NetworkMDNSRegister::DNSServiceDeallocator {
     void operator()(DNSServiceRef service) const { DNSServiceRefDeallocate(service); }
@@ -59,11 +64,6 @@ void NetworkMDNSRegister::unregisterMDNSNames(WebCore::ScriptExecutionContextIde
         m_registeredNames.remove(name);
 }
 
-bool NetworkMDNSRegister::hasRegisteredName(const String& name) const
-{
-    return m_registeredNames.contains(name);
-}
-
 struct PendingRegistrationRequest {
     WTF_MAKE_STRUCT_FAST_ALLOCATED;
     PendingRegistrationRequest(Ref<NetworkConnectionToWebProcess>&& connection, String&& name, PAL::SessionID sessionID, CompletionHandler<void(const String&, std::optional<WebCore::MDNSRegisterError>)>&& completionHandler)