Comment out some more MacOS lines that may have been unintentional

These have been building on MacOS for a very long time, and although
there were exclusions listed in .travis.yml, they were not exactly identical
to the matrix above it, so they were not excluded.

Comment them out, I see no reason why they cannot be tested as they have been.

.travis.yml

@@ -97,10 +97,10 @@ matrix:
     env: MVM_OPTIONS="--has-libffi --no-jit"  CC='gcc'
   - os: osx
     env: MVM_OPTIONS="--has-libffi"           CC='gcc'
-  - os: osx
-    env: MVM_OPTIONS="--no-jit"               CC='gcc'
-  - os: osx
-    env: MVM_OPTIONS=""                       CC='gcc'
+#  - os: osx
+#    env: MVM_OPTIONS="--no-jit"               CC='gcc'
+#  - os: osx
+#    env: MVM_OPTIONS=""                       CC='gcc'
   - os: osx
     env: MVM_OPTIONS="--has-libffi --no-jit"  CC='clang'
   - os: osx