[SYCL] Can't cancel sycl-xocc driver script

[agozillon]

One side affect of using a script to help drive our ToolChain at the moment is that CTRL-C inside of a terminal to cancel the compilation will not always cancel the currently executing script process, it will continue to fire in the background until complete. This is particularly notable when compiling a lot of kernels in a single source file e.g. the reqd_work_group_size.cpp test. A solution to this will require further investigation.