optipng: fix 10.10 build
Added libomp formula for 64 bit OS X.
simplified script
support for 32bit, see https://github.com/Homebrew/homebrew/pull/33118#discussion_r18749144
- :arch => :intel - corrected indentation
libomp: add 20140926 bottle.
optipng: add 0.7.5 bottle.