Disable piglit test for sub-buffers.
Disable piglit test for sub-buffers.

It has a hard-coded alignment for subbuffers which is
incompatible with pocl's basic/pthread required alignment.

Oblomov/pocl,Oblomov/pocl,Oblomov/pocl,Oblomov/pocl,pocl/pocl,franz/pocl,pocl/pocl,pocl/pocl,pocl/pocl,franz/pocl,pocl/pocl,franz/pocl,Oblomov/pocl,franz/pocl,franz/pocl