appveyor change

.appveyor.yml

@@ -1,8 +1,10 @@
 environment:
   RUST_BACKTRACE: 1
+  OPENSSL_DIR C:\Tools\vcpkg\packages\openssl-windows_x64-windows
+  BSON_LIB C:\Tools\vcpkg\packages\libbson_x64-windows\lib
+  MONGO_LIB C:\Tools\vcpkg\packages\mongo-c-driver_x64-windows\lib
   matrix:
   - TARGET: x86_64-pc-windows-msvc
-  - TARGET: x86_64-pc-windows-gnu
 install:
   - curl -sSf -o rustup-init.exe https://win.rustup.rs/
   - rustup-init.exe -y --default-host %TARGET%
@@ -10,6 +12,13 @@ install:
 
   - rustc -vV
   - cargo -vV
+
+  - cd C:\Tools\vcpkg
+  - git pull
+  - .\bootstrap-vcpkg.bat
+  - vcpkg install openssl::x64-windows
+  - vcpkg install mongo-c-driver:x64-windows
+
 build: false
 test_script:
   - cargo build