Remove libc++.dll.a to enforce static linking to libc++

Newer GHC bindists on Windows come with clang and libc++ instead of gcc and libstdc++.

When linking, `.dll.a` files take precedence over the normal `.a` files and cause the
resulting binary to depend on the corresponding DLL at runtime.

Removing the files causes the linker to pick up the proper static library instead.

haskell/ghc_bindist.bzl

@@ -122,6 +122,9 @@ def _ghc_bindist_impl(ctx):
         # on //tests/haddock:haddock-lib-b.
         dll_a_libs.append("libz.dll.a")
 
+        # Similarly causes loading issues when using libc++ with clang on GHC >= 9.4
+        dll_a_libs.append("libc++.dll.a")
+
         # It's hard to guesss the paths of these libraries, so we have to use
         # dir to recursively find them.
         for lib in dll_a_libs: