set the winsock variable differently on Windows

external/CMakeLists.txt

@@ -100,11 +100,12 @@ IF(!UNBOUND_INCLUDE_DIR OR STATIC)
   ENDIF()
   
   IF(MINGW)
+    set(ENV{USE_WINSOCK} 1)
     EXTERNALPROJECT_ADD(
       libunbound
       PREFIX ${CMAKE_CURRENT_BINARY_DIR}/unbound
       URL ${CMAKE_CURRENT_SOURCE_DIR}/unbound/
-      CONFIGURE_COMMAND COMMAND ${CMAKE_CURRENT_SOURCE_DIR}/unbound/configure USE_WINSOCK=1 --prefix=${CMAKE_FIND_ROOT_PATH} --build=${GCC_PREFIX} --host=${GCC_PREFIX} --disable-shared --enable-static --sysconfdir=${CMAKE_FIND_ROOT_PATH}/etc --localstatedir=${CMAKE_FIND_ROOT_PATH}/var --sbindir=${CMAKE_FIND_ROOT_PATH}/bin --disable-gost --disable-rpath --with-libevent=no --with-libexpat=${CMAKE_FIND_ROOT_PATH} --without-pyunbound --without-pythonmodule --with-ssl=${CMAKE_FIND_ROOT_PATH} --without-pthreads --with-libunbound-only
+      CONFIGURE_COMMAND ${CMAKE_CURRENT_SOURCE_DIR}/unbound/configure --prefix=${CMAKE_FIND_ROOT_PATH} --build=${GCC_PREFIX} --host=${GCC_PREFIX} --disable-shared --enable-static --sysconfdir=${CMAKE_FIND_ROOT_PATH}/etc --localstatedir=${CMAKE_FIND_ROOT_PATH}/var --sbindir=${CMAKE_FIND_ROOT_PATH}/bin --disable-gost --disable-rpath --with-libevent=no --with-libexpat=${CMAKE_FIND_ROOT_PATH} --without-pyunbound --without-pythonmodule --with-ssl=${CMAKE_FIND_ROOT_PATH} --without-pthreads --with-libunbound-only
       BUILD_COMMAND $(MAKE)
       UPDATE_COMMAND ""
       PATCH_COMMAND ""