Updated AppVeyor path configuration.

Author: ibabushkin

appveyor.yml

@@ -4,7 +4,7 @@ environment:
     OTHER_TARGET: i686-pc-windows-msvc
 
 install:
-  - set PATH=C:\Program Files\Git\mingw64\bin;%PATH%
+  - set PATH=%PATH%;C:\Program Files\Git\mingw64\bin
   - curl -sSf -o rustup-init.exe https://win.rustup.rs/
   - rustup-init.exe -y --default-host %TARGET% --default-toolchain nightly
   - set PATH=%PATH%;C:\Users\appveyor\.cargo\bin;C:\Users\appveyor\.rustup\toolchains\nightly-%TARGET%\bin