tools: travis: try some changes seen on stack list

.travis.yml

@@ -5,6 +5,12 @@ branches:
     - master
 
 sudo: false
+
+# addons:
+#   apt:
+#     packages:
+#     - libgmp-dev
+
 cache:
   directories:
     - $HOME/.stack/
@@ -16,12 +22,15 @@ before_install:
   - travis_retry curl -L https://github.com/commercialhaskell/stack/releases/download/v0.1.3.1/stack-0.1.3.1-x86_64-linux.gz | gunzip > ~/.local/bin/stack
   - chmod a+x ~/.local/bin/stack
 
-install:
-  - stack setup
-  - stack build --only-snapshot
+# install:
+#   - stack setup
+#   - stack build --only-snapshot
+
+# script:
+#   - stack build --test
 
 script:
-  - stack build --test
+  - stack +RTS -N2 -RTS --install-ghc --no-terminal build --test
 
 # coveralls.io coverage reports
 # after_script: