trying to fix compile on win32 witout fltk

CMakeLists.txt

@@ -779,6 +779,10 @@ if(MSVC)
   list(APPEND EXTERNAL_LIBRARIES "ws2_32")
 endif(MSVC)
 
+if(WIN32 AND NOT HAVE_FLTK)
+  list(APPEND EXTERNAL_LIBRARIES "ws2_32 wsock32")
+endif(WIN32 AND NOT HAVE_FLTK)
+
 list(SORT CONFIG_OPTIONS)
 set(GMSH_CONFIG_OPTIONS "")
 foreach(OPT ${CONFIG_OPTIONS})