Don't pass both CMAKE_TOOLCHAIN_FILE and a preset.

Author: alexreinking

master/master.cfg

@@ -432,8 +432,6 @@ def get_cmake_definitions(builder_type, halide_target="host", wasm_jit="wabt", e
     if builder_type.has_ccache():
         cmake_definitions["Halide_CCACHE_BUILD"] = "ON"
 
-    cmake_definitions["CMAKE_TOOLCHAIN_FILE"] = Interpolate("%(prop:VCPKG_ROOT)s/scripts/buildsystems/vcpkg.cmake")
-
     if builder_type.os == "windows":
         cmake_definitions["pybind11_ROOT"] = Property("VIRTUAL_ENV")