Windows debug builds of vncviewer should have a console

Makes it easier to debug it by having convenient access to the
log output.
diff --git a/vncviewer/CMakeLists.txt b/vncviewer/CMakeLists.txt
index 9b815a3..ca1fbaf 100644
--- a/vncviewer/CMakeLists.txt
+++ b/vncviewer/CMakeLists.txt
@@ -41,7 +41,7 @@
   set(VNCVIEWER_SOURCES ${VNCVIEWER_SOURCES} X11PixelBuffer.cxx)
 endif()
 
-if(WIN32)
+if(WIN32 AND NOT CMAKE_BUILD_TYPE STREQUAL "Debug")
   add_executable(vncviewer WIN32 ${VNCVIEWER_SOURCES})
 else()
   add_executable(vncviewer ${VNCVIEWER_SOURCES})