Fix compilation with VS2017

Enable OpenSubdiv by default for VS2019(CMakeSettings.json)

CMakeSettings.json

@@ -15,6 +15,11 @@
           "name": "TINYUSDZ_USE_CCACHE",
           "value": "False",
           "type": "BOOL"
+        },
+        {
+          "name": "TINYUSDZ_WITH_OPENSUBDIV",
+          "value": "True",
+          "type": "BOOL"
         }
       ]
     },

README.md

@@ -56,7 +56,9 @@ Recomended way is simply copy `src` and `include` folder to your app, and add `*
 
 ### CMake
 
-cmake build is still provided for CI build. Cmake project is not recommended for embedding TinyUSDZ to your app.
+cmake build is still provided for CI build. `CMakeSettings.json` is provided for Visual Studio 2019.
+
+Cmake project is not recommended for embedding TinyUSDZ to your app.
 
 ```
 $ mkdir build

src/tinyusdz.cc

@@ -29,6 +29,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <algorithm>
 #include <atomic>
 #include <cassert>
+#include <cctype> // std::tolower
 #include <chrono>
 #include <fstream>
 #include <map>

vcsetup-2017.bat

@@ -0,0 +1,4 @@
+rmdir /s /q build
+mkdir build
+
+cmake -G "Visual Studio 15 2017" -A x64 -Bbuild -H.