Use a shared namespace for shader and program objects.

Bug 19219444

Change-Id: I5eb797eed31ab233866e5c23d83298d3c57091a9
Reviewed-on: https://swiftshader-review.googlesource.com/4989
Reviewed-by: Alexis Hétu <sugoi@google.com>
Tested-by: Nicolas Capens <capn@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>