adding formula for glbinding

see https://github.com/hpicgs/glbinding
These two failures are encompassed by `needs :cxx11`: https://github.com/Homebrew/homebrew/blob/1f7128f50e0f007d827ca4df78aa4db200dfb416/Library/Homebrew/compilers.rb#L52-60

`:gcc` means only Apple's GCC 4.2. GNU GCCs are specified like `:gcc => "4.x"`. However, gcc 4.7 and greater should be capable of compiling any C++11 code.