CMake: Fix build when HAVE_DNS_SD and no network backend

When HAVE_DNS_SD is set to ON in the config, and then
WITH_NETWORK_BACKEND is set to OFF, the library wouldn't build.

Signed-off-by: Paul Cercueil <[email protected]>

Author: pcercuei

CMakeLists.txt

@@ -368,6 +368,7 @@ if(WITH_NETWORK_BACKEND)
 	set(NEED_LIBXML2 1)
 else()
 	message(STATUS "Building without network support")
+	set(HAVE_DNS_SD OFF)
 endif()