Fixed gcc multi os directory command line argument syntax

Changed --print-multi-os-dir to --print-multi-os-dirrectory in both
formulae
Changed ppl library dependency declaration to correct package name

Changed ppl to ppl10 as the dependency's package name
Merge pull request #1 from charlesfracchia/master

Make the formula work with both clang and gcc.
Also update the ppl dependency, which has been renamed in homebrew.