wip add explicit homebrew command for libsodium

Author: winitzki

.travis.yml

@@ -22,13 +22,9 @@ branches:
   - master
   - /^\d+\.\d+\.\d+(\.\d+)?$/
 
-addons:
-  homebrew:
-    packages:
-    - libsodium
-    update: true
-
 before_install:
+  - arch -x86_64 /usr/local/bin/brew update
+  - arch -x86_64 /usr/local/bin/brew install libsodium
   # Using compiler above sets CC to an invalid value, so unset it
   - unset CC
   - CABALARGS=""