GBE: don't enable double by default.
GBE: don't enable double by default.

Actually, we don't support double completely currently.
Let's disable it now. This bring a little incompatible point with the 1.2 spec
which doesn't require the kernel to use the following pragma to enable fp64.
 #pragma OPENCL EXTENSION cl_khr_fp64 : enable

If the application wants to try the partially supported double with beignet
under opencl 1.2, the application will still need to add the above pragma.

Signed-off-by: Zhigang Gong <e04a7b9b70b1e4c6318cf117dcd1a9056e14b97a@intel.com>
Reviewed-by: "Yang, Rong R" <78759e37dc7114caed18f74e7515c5cb519dbf6d@intel.com>

freedesktop-unofficial-mirror/beignet,freedesktop-unofficial-mirror/beignet,wdv4758h/beignet,wdv4758h/beignet,zhenyw/beignet,wdv4758h/beignet,zhenyw/beignet,zhenyw/beignet,zhenyw/beignet,freedesktop-unofficial-mirror/beignet,wdv4758h/beignet,wdv4758h/beignet,zhenyw/beignet,freedesktop-unofficial-mirror/beignet