do msys2 system upgrade in appveyor

.appveyor.yml

@@ -11,8 +11,8 @@ cache:
 
 before_build:
   - git submodule update --init --recursive
-#  - C:\msys64\usr\bin\bash -lc "PATH=/mingw64/bin:/usr/local/bin:/usr/bin:/bin:$PATH && pacman --noconfirm --ask 20 --sync --refresh --sysupgrade"
-#  - C:\msys64\usr\bin\bash -lc "PATH=/mingw64/bin:/usr/local/bin:/usr/bin:/bin:$PATH && pacman --noconfirm --sync --refresh pacman git"
+  - C:\msys64\usr\bin\bash -lc "PATH=/mingw64/bin:/usr/local/bin:/usr/bin:/bin:$PATH && pacman --noconfirm --ask 20 --sync --refresh --sysupgrade"
+  - C:\msys64\usr\bin\bash -lc "PATH=/mingw64/bin:/usr/local/bin:/usr/bin:/bin:$PATH && pacman --noconfirm --sync --refresh pacman git"
   - C:\msys64\usr\bin\bash -lc "export PATH=/mingw64/bin:/usr/local/bin:/usr/bin:/bin && pacman --noconfirm --needed --sync make mingw-w64-x86_64-{cmake,toolchain,clang,gtkmm3,gtksourceviewmm3,boost,aspell,aspell-en,libgit2}"
 
 build_script: