Windows: Upgrade bundled MinGW-based libs to v8.0.0

Author: kinke

.azure-pipelines/windows.yml

@@ -147,7 +147,7 @@ steps:
   displayName: Install LDC, make portable & copy curl
 - script: |
     cd ..
-    curl -L -o mingw-w64-libs.7z https://github.com/ldc-developers/mingw-w64-libs/releases/download/v7.0.0/mingw-w64-libs-v7.0.0.7z 2>&1
+    curl -L -o mingw-w64-libs.7z https://github.com/ldc-developers/mingw-w64-libs/releases/download/v7.0.0/mingw-w64-libs-v8.0.0.7z 2>&1
     mkdir mingw-w64-libs
     cd mingw-w64-libs
     7z x ../mingw-w64-libs.7z > nul