Add libgl1 package dependency for Travis CI.

Author: svenpanne

.travis.yml

@@ -1,6 +1,6 @@
 # This Travis job script has been generated by a script via
 #
-#   haskell-ci 'OpenGL.cabal' '--output' '.travis.yml'
+#   haskell-ci 'OpenGL.cabal' '--output' '.travis.yml' '--apt' 'libgl1'
 #
 # For more information, see https://github.com/haskell-CI/haskell-ci
 #
@@ -27,20 +27,20 @@ before_cache:
 matrix:
   include:
     - compiler: ghc-8.8.1
-      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-8.8.1","cabal-install-3.0"]}}
+      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-8.8.1","cabal-install-3.0","libgl1"]}}
       env: GHCHEAD=true
     - compiler: ghc-8.6.5
-      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-8.6.5","cabal-install-2.4"]}}
+      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-8.6.5","cabal-install-2.4","libgl1"]}}
     - compiler: ghc-8.4.3
-      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-8.4.3","cabal-install-2.4"]}}
+      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-8.4.3","cabal-install-2.4","libgl1"]}}
     - compiler: ghc-8.2.2
-      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-8.2.2","cabal-install-2.4"]}}
+      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-8.2.2","cabal-install-2.4","libgl1"]}}
     - compiler: ghc-8.0.2
-      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-8.0.2","cabal-install-2.4"]}}
+      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-8.0.2","cabal-install-2.4","libgl1"]}}
     - compiler: ghc-7.10.3
-      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-7.10.3","cabal-install-2.4"]}}
+      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-7.10.3","cabal-install-2.4","libgl1"]}}
     - compiler: ghc-7.8.4
-      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-7.8.4","cabal-install-2.4"]}}
+      addons: {"apt":{"sources":["hvr-ghc"],"packages":["ghc-7.8.4","cabal-install-2.4","libgl1"]}}
   allow_failures:
     - compiler: ghc-8.8.1
 before_install:
@@ -158,5 +158,5 @@ script:
   - rm -f cabal.project.local
   - ${CABAL} v2-build -w ${HC} --disable-tests --disable-benchmarks all | color_cabal_output
 
-# REGENDATA ["OpenGL.cabal","--output",".travis.yml"]
+# REGENDATA ["OpenGL.cabal","--output",".travis.yml","--apt","libgl1"]
 # EOF