Make cc_configure on Windows more robust
Make cc_configure on Windows more robust

1. Throw an error if Bash-on-Windows is found instead of MSYS bash
2. Introduce BAZEL_VS environment variable
3. Output more information

Fix https://github.com/bazelbuild/bazel/issues/1847

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Change-Id: Ic4571c6c792d9b81df4cd800b8f19d121cc44c33
Reviewed-on: https://bazel-review.googlesource.com/#/c/6330
MOS_MIGRATED_REVID=134531295

davidzchen/bazel-website,bazelbuild/bazel-website,davidzchen/bazel-website,bazelbuild/bazel-website,davidzchen/bazel-website,davidzchen/bazel-website,bazelbuild/bazel-website