GHA/windows: avoid curl.exe libtool wrapper

Avoid the `curl.exe` wrapper binary created by libtool, and run the real
`curl.exe` directly for tests and version information.

This solution was used in Azure jobs. I missed it when migrating jobs
to GHA.

Applies to tests run in the `mingw, AM x86_64 c-ares U` job, which has
seen unexplained flakiness.

Ref: 354afc891d #6049
Follow-up to e53523fef0 #14859

Closes #15437

.github/workflows/windows.yml

@@ -274,6 +274,9 @@ jobs:
         if: ${{ matrix.build == 'autotools' }}
         timeout-minutes: 1
         run: |
+          # avoid libtool's curl.exe wrapper
+          mv bld/src/.libs/curl.exe bld/src/curl.exe
+          mv bld/lib/.libs/*.dll bld/src || true
           find . -name '*.exe' -o -name '*.dll'
           bld/src/curl.exe --disable --version