Should add --HEAD option when install mozart2 using brew

Otherwise brew would complain that mozart2 is a head-only formula.
Merge pull request #218 from suzaku/patch-1

Should add --HEAD option when install mozart2 using brew
Maybe fixed a bug which caused SEGFAULT when using gcDo on a -g *.ozf.
Avoid generating `getSelf`/`setSelf` instructions for class with locking.