Fix Monolithic build on Windows

Configure MaterialX with MATERIALX_BUILD_MONOLITHIC=ON on Windows, building this with with VS2022 causes couple issues:
1. error C1128: number of sections exceeded object file format
  fixed by adding /bigobj flag
2. Linker error from MaterialX_v1_39_0::OiioImageLoader::saveImage()
  fixed by muting OiioImageLoader using MATERIALX_BUILD_OIIO

CMakeLists.txt

@@ -236,6 +236,7 @@ endif()
 # Adjust compiler settings
 if(MSVC)
     add_compile_options(/MP)
+    add_compile_options(/bigobj)
     if(CMAKE_CXX_FLAGS MATCHES "/W[0-4]")
         string(REGEX REPLACE "/W[0-4]" "/W4" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
     else()

source/MaterialXRender/OiioImageLoader.h

@@ -5,7 +5,8 @@
 
 #ifndef MATERIALX_OIIOIMAGELOADER_H
 #define MATERIALX_OIIOIMAGELOADER_H
-
+
+#if MATERIALX_BUILD_OIIO
 /// @file
 /// Image loader wrapper using OpenImageIO
 
@@ -55,5 +56,5 @@ class MX_RENDER_API OiioImageLoader : public ImageLoader
 };
 
 MATERIALX_NAMESPACE_END
-
+#endif //MATERIALX_BUILD_OIIO
 #endif