cgl: avoid leaking the PixelFormat
cgl: avoid leaking the PixelFormat

According to apple developer page, starting with OS X v10.5 the
pixelformat is reference counted. The object is created at
CGLChoosePixelFormat and should be unrefeferenced via
CGLReleasePixelFormat/CGLDestroyPixelFormat.

The latter two are identical accoring to the documentation.

Signed-off-by: Emil Velikov <4c996f2f093ddd0585a556460b4cc3ba555546ef@gmail.com>
Reviewed-by: Chad Versace <a557f7f75bf28dc19ac99107f5cc7cd6b3fbdb1a@linux.intel.com>

evelikov/waffle,chadversary/waffle,fjhenigman/waffle,yinquan529/waffle-gl-waffle,chadversary/waffle,yinquan529/waffle-gl-waffle,chadversary/waffle,dcbaker/waffle,evelikov/waffle,janesma/waffle,waffle-gl/waffle,evelikov/waffle,fjhenigman/waffle,dcbaker/waffle,fjhenigman/waffle,waffle-gl/waffle,janesma/waffle,waffle-gl/waffle,yinquan529/waffle-gl-waffle,maurossi/waffle,maurossi/waffle,waffle-gl/waffle,maurossi/waffle,dcbaker/waffle,janesma/waffle