Revert "more fixes for compilation on Mac OS X with OCaml 4.02.0"

This reverts commit 2fe92dd61a02e832e7e49c30457456b291615ffc.
Revert "added tentative fix for compilation on Mac OS X with OCaml 4.02.0"

This reverts commit 66a39e10e3e148e1106c08657b96830a30374fef.