Properly release context on clReleaseMemObject
Properly release context on clReleaseMemObject

The context needs to be properly freed if the release brings its
refcount to zero, and this is done by clReleaseContext, so call that
instead of the built-in macro.

vkorhonen/pocl,Oblomov/pocl,pocl/pocl,pocl/pocl,rjodin/pocl,rjodin/pocl,pavanky/pocl,dsandersimgtec/pocl,vkorhonen/pocl,rjodin/pocl,jrprice/pocl,Oblomov/pocl,jrprice/pocl,franz/pocl,jrprice/pocl,franz/pocl,Oblomov/pocl,dsandersimgtec/pocl,pavanky/pocl,franz/pocl,pocl/pocl,Oblomov/pocl,franz/pocl,dsandersimgtec/pocl,rjodin/pocl,dsandersimgtec/pocl,Oblomov/pocl,jrprice/pocl,pavanky/pocl,pocl/pocl,franz/pocl,pavanky/pocl,vkorhonen/pocl,vkorhonen/pocl,pocl/pocl