[Pkg-opencl-devel] Bug#768090: beignet: pow/erf/tgamma, GBE_DEBUG, constants bug

[Rebecca N. Palmer]

Fix committed to Alioth.

This fix has been accepted upstream; they found that it exposed another 
bug that compare and type-convert don't properly handle constants 
(http://lists.freedesktop.org/archives/beignet/2014-November/004387.html), 
so I included the fix for that as well.

My own testing had missed this because GBE_DEBUG was off in our build, 
probably by accident (debhelper's default build type fairly recently 
changed from RelWithDebInfo to None, see #701233) and the test data used 
in compiler_constant_expr are all positive; I've turned it on again as 
I'd rather have an obvious error than silently broken code.