Minor tweaks.

Former-commit-id: a99bc6a2eb069c6839c397ff04c629e7ed588895

.appveyor.yml

@@ -17,7 +17,7 @@ build_script:
   - cd external
   - mkdir build
   - cd build
-  - cmake ..
+  - cmake -G "Visual Studio 15 2017 Win64" -T "host=x64" ..
   - msbuild %MSBuildOptions% libigl_external.sln
   - cd ../../tutorial
   - mkdir build

shared/cmake/libigl.cmake

@@ -149,7 +149,7 @@ if(LIBIGL_WITH_CGAL)
   if(EXISTS ${LIBIGL_EXTERNAL}/boost)
     set(BOOST_ROOT "${LIBIGL_EXTERNAL}/boost")
   endif()
-  find_package(CGAL REQUIRED COMPONENTS Core)
+  find_package(CGAL COMPONENTS Core)
   if(CGAL_FOUND)
     compile_igl_module("cgal")
     if(WIN32)