Try using clang64 environment packages

ghc-toolchain.py

@@ -11,8 +11,7 @@ import shutil
 Arch = NewType('Arch', str)
 Url = str
 
-#UPSTREAM_URL = 'http://repo.msys2.org/mingw'
-UPSTREAM_URL = 'https://mirror.selfnet.de/msys2/mingw'
+UPSTREAM_URL = 'http://mirror.msys2.org/mingw'
 
 CHECK_SIGNATURES = False
 JAILBREAK = Path('ghc-jailbreak')
@@ -23,8 +22,8 @@ ARCHS = ['x86_64', 'sources'] # type: List[Arch] valid entries x86_64, i686, sou
 def package(name: str, archs: List[Arch] = ARCHS, ext: str = 'zst') -> Dict[Arch, Url]:
     # N.B. ext is to accomodate transition from .xz to .zst archives.
     URLS = {
-        'x86_64':  f'/x86_64/mingw-w64-x86_64-{name}-any.pkg.tar.{ext}',
-        'i686':  f'/i686/mingw-w64-i686-{name}-any.pkg.tar.{ext}',
+        'x86_64':  f'/clang64/mingw-w64-clang-x86_64-{name}-any.pkg.tar.{ext}',
+        'i686':  f'/clang32/mingw-w64-clang-i686-{name}-any.pkg.tar.{ext}',
         'sources':  f'/sources/mingw-w64-{name}.src.tar.gz',
     }
     return { arch: URLS[arch] for arch in archs }
@@ -39,11 +38,10 @@ llvm_ver = '13.0.0-3'
 packages = [
     package(f'crt-git-{crt_ver}-1'),
     package(f'headers-git-{crt_ver}-1'),
-    package('zstd-1.4.5-1'),
-    package('windows-default-manifest-6.4-3', ext='xz'),
+    package('zstd-1.5.2-2'),
+    package('windows-default-manifest-6.4-4'),
 
     # dependencies of Clang/LLVM
-    package('gcc-libs-11.2.0-10', archs=['i686', 'x86_64']),
     package('libxml2-2.9.13-1', archs=['i686', 'x86_64']),
     package('libffi-3.3-4', archs=['i686', 'x86_64']),
     package(f'libwinpthread-git-{winpthreads_ver}', archs=['i686', 'x86_64']),