The VS 2019 CMake generator no longer has different generator types for
different architectures. Now, the architecture is specified via CMake's
`-A` switch. However, this requires we also propagate
`${CMAKE_GENERATOR_PLATFORM}` to the bundled deps, so they build for the
same architecture as Nvim.
Avoids having CMakeCache.txt etc in https://github.com/neovim/deps, where it can cause trouble for Ubuntu PPA builds such as:
> CMake Error: The source "/<<BUILDDIR>>/neovim-0.5.0+ubuntu1+git202002090924-1f479ff-00e710e/.deps/build/src/treesitter-c/CMakeLists.txt" does not match the source "/home/travis/build/neovim/bot-ci/build/deps-src/build/src/treesitter-c/CMakeLists.txt" used to generate cache. Re-run cmake with a different source directory.
if USE_BUNDLED_TS_PARSERS is set to off, don't try to install the
parser.
Distribs can install treesitter parsers directly into $CMAKE_LIBRARY_PATH/nvim
(and users anywhere in rtp).
Also fix the URL.
