CI: use absolute qt5 path for cmake, install GL libs again

Author: lateleite

appveyor.yml

@@ -7,9 +7,9 @@ image:
 environment:
   matrix:
     - BUILD_COMBO: linux-gcc
-      CMAKE_PREFIX_PATH: "$HOME/Qt/5.14/gcc_64"
+      CMAKE_PREFIX_PATH: "/home/appveyor/Qt/5.14/gcc_64"
     - BUILD_COMBO: linux-clang
-      CMAKE_PREFIX_PATH: "$HOME/Qt/5.14/clang_64"
+      CMAKE_PREFIX_PATH: "/home/appveyor/Qt/5.14/gcc_64"
     - BUILD_COMBO: windows-mingw
       CMAKE_PREFIX_PATH: "C:\\Qt\\5.14\\mingw73_64"
     - BUILD_COMBO: windows-msvc

ci/setup.ps1

@@ -79,7 +79,7 @@ if ($isLinux) {
     # sudo apt install -y ninja-build
 
     # install GL libs required by qt
-    # sudo apt install -y libgl1-mesa-dev mesa-common-dev
+    sudo apt install -y libgl1-mesa-dev mesa-common-dev
 
     # install qt
     # sudo add-apt-repository "ppa:beineri/opt-qt-5.12.3-xenial"