Fix sha256sum issue on Windows

git was automatically converting `\n` lineendings to `\r\n`, which
confused `sha256sum`. By declaring `.sha256` files as binary
`.gitattributes` we avoid this issue.

.ci/fetch-bazel-bindist

@@ -11,20 +11,7 @@ esac
 VERSION=$(cat "$TOP/.ci/bazelversion")
 INSTALL="$(mktemp -d)"
 (cd "$INSTALL" && curl -LO "https://github.com/bazelbuild/bazel/releases/download/$VERSION/bazel-$VERSION-$OS$EXT" >&2)
-if [[ $OS = windows-x86_64 ]]; then
-  # sha256sum -c does not behave as expected on Windows. It produces
-  #
-  #   sha256sum: /d/a/1/s/.ci/bazel-sha256: no file was verified
-  #
-  # even when the hashes match upon manual inspection.
-  SHA256="$(cd "$INSTALL" && sha256sum --text bazel-$VERSION-$OS$EXT)"
-  if ! grep -q "$SHA256" "$TOP/.ci/bazel-$VERSION-$OS$EXT.sha256" >&2; then
-    echo "sha256 mismatch (compare .ci/bazel-sha256): $SHA256" >&2
-    exit 1
-  fi
-else
-  (cd "$INSTALL" && sha256sum --quiet -c "$TOP/.ci/bazel-$VERSION-$OS$EXT.sha256") >&2
-fi
+(cd "$INSTALL" && sha256sum --quiet -c "$TOP/.ci/bazel-$VERSION-$OS$EXT.sha256") >&2
 mv "$INSTALL/bazel-$VERSION-$OS$EXT" "$INSTALL/bazel$EXT"
 chmod +x "$INSTALL/bazel$EXT"
 echo -n "$INSTALL"

.gitattributes

@@ -0,0 +1,3 @@
+# Prevent git from automatically introducing \r characters in .sha256 files.
+# Otherwise msys sha256sum fails.
+*.sha256 binary