[git-credential-luci] Redirect to batch file on Windows

I believe Git will try to run the file without extension (this bash
file) directly, which causes issues.

Bug: 410753790
Change-Id: I3a43dfd84e6459f64a023d3c656d8d3ff3b7bd5e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/6463456
Commit-Queue: Allen Li <ayatane@chromium.org>
Reviewed-by: Yiwei Zhang <yiwzhang@google.com>

git-credential-luci

@@ -6,6 +6,12 @@
 
 # See revert instructions in cipd_manifest.txt
 
+# In git bash on Windows, invoke the batch file.
+if [ "$(expr "$(uname -s)" : "^MINGW64_NT")" == "10" ]; then
+    git-credential-luci.bat "$@"
+    exit
+fi
+
 MYPATH=$(dirname "${BASH_SOURCE[0]}")
 
 source "$MYPATH/cipd_bin_setup.sh"