Merge pull request google#539 from google/draco_win_dll_link_fix

draco cmake: Defer windows shared lib check until after plugin checks.

CMakeLists.txt

@@ -56,11 +56,6 @@ option(BUILD_FOR_GLTF "" OFF)
 option(BUILD_MAYA_PLUGIN "Build plugin library for Maya." OFF)
 option(BUILD_USD_PLUGIN "Build plugin library for USD." OFF)
 
-if(WIN32 AND BUILD_SHARED_LIBS)
-  set(CMAKE_WINDOWS_EXPORT_ALL_SYMBOLS TRUE)
-  include(GenerateExportHeader)
-endif()
-
 if(BUILD_FOR_GLTF)
   # Override settings when building for GLTF.
   draco_enable_feature(FEATURE "DRACO_MESH_COMPRESSION_SUPPORTED")
@@ -137,6 +132,10 @@ if(BUILD_USD_PLUGIN)
   draco_enable_feature(FEATURE "BUILD_USD_PLUGIN")
 endif()
 
+if(WIN32 AND BUILD_SHARED_LIBS)
+  set(CMAKE_WINDOWS_EXPORT_ALL_SYMBOLS TRUE)
+endif()
+
 if(ENABLE_EXTRA_SPEED)
   if(MSVC)
     # Maximum optimization in Release mode.