temporarily remove travis osx builds

Travis has built up a huge backlog and building for osx takes days atm.

.travis.yml

@@ -45,13 +45,13 @@ matrix:
     - os: linux
       compiler: clang
       env: FUZZER=true
-    - os: osx
-      compiler: clang
-      # disable homebrew auto update which takes a lot of time
-      env: HOMEBREW_NO_AUTO_UPDATE=1
-      cache:
-        directories:
-          - $HOME/Library/Caches/Homebrew
+    # - os: osx
+    #   compiler: clang
+    #   # disable homebrew auto update which takes a lot of time
+    #   env: HOMEBREW_NO_AUTO_UPDATE=1
+    #   cache:
+    #     directories:
+    #       - $HOME/Library/Caches/Homebrew
 
 addons:
   apt: