Fix SPIR examples: use -finclude-default-header instead of PoCL's headers
Fix SPIR examples: use -finclude-default-header instead of PoCL's headers

This is necessary because PoCL renames library function names,
and we want the SPIR bitcode to refer to SPIR names not PoCL names.

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