Run windows build with c++17 to avoid the protobuf compile issues. Also, bump the LLVM version a bit (it's relatively new already)

Author: ivan444

.bazelrc

@@ -24,8 +24,7 @@ common:macos --features=-supports_dynamic_linker --linkopt=-framework --linkopt=
 # so we focus the effort for now is to have a Windows Verible compiled with
 # clang-cl before fixing the issues unique to MSVC.
 common:windows --extra_toolchains=@local_config_cc//:cc-toolchain-x64_windows-clang-cl --extra_execution_platforms=//:x64_windows-clang-cl
-# Since we use designated initializers (C99 ... but >= c++20), compiler really wants the c++20 mode
-common:windows --compiler=clang-cl --cxxopt=/std:c++20 --host_cxxopt=/std:c++20 --client_env=BAZEL_CXXOPTS=/std:c++20
+common:windows --compiler=clang-cl --cxxopt=/std:c++17 --host_cxxopt=/std:c++17 --client_env=BAZEL_CXXOPTS=/std:c++17
 
 build --cxxopt="-Wno-unknown-warning-option" --host_cxxopt="-Wno-unknown-warning-option"
 # TODO: this looks like benign where it happens but to be explored further.

.github/workflows/verible-ci.yml

@@ -398,7 +398,7 @@ jobs:
       run: |
         choco install bazel --force --version=7.6.1
         choco install winflexbison3
-        choco install llvm --allow-downgrade --version=20.1.3
+        choco install llvm --allow-downgrade --version=20.1.4
 
     - name: Debug bazel directory settings
       # We need to explicitly call the bazel binary from choco, otherwise