Small tidy up on MySQL binary column type generation
Small tidy up on MySQL binary column type generation

I've refactored the changes from #12552 to reduce nesting and
complexity. I felt the original schema generation change was safe for
3.6 as it should generally only effect test suite schema generation.

davidyell/cakephp,CakeDC/cakephp,dakota/cakephp,mvdriel/cakephp,petteyg/cakephp,cakephp/cakephp,garethellis36/cakephp,ndm2/cakephp,petteyg/cakephp,mvdriel/cakephp,ADmad/cakephp,CakeDC/cakephp,ADmad/cakephp,ndm2/cakephp,cakephp/cakephp,dakota/cakephp,tenkoma/cakephp,garethellis36/cakephp,cakephp/cakephp,petteyg/cakephp,dakota/cakephp,tenkoma/cakephp,tenkoma/cakephp,davidyell/cakephp,mvdriel/cakephp,CakeDC/cakephp,davidyell/cakephp,ndm2/cakephp,ADmad/cakephp,ndm2/cakephp,tenkoma/cakephp,garethellis36/cakephp,cakephp/cakephp,garethellis36/cakephp,ADmad/cakephp,mvdriel/cakephp,CakeDC/cakephp,dakota/cakephp,petteyg/cakephp