graphite: Accept loops without data references

graphite: Accept loops without data references

It seems that the check that rejects loops without data references is
only included to avoid handling non-profitable loops.  Including those
loops in Graphite's analysis enables more consistent diagnostic
messages in OpenACC "kernels" code and does not introduce any
testsuite regressions.  If executing Graphite on loops without
data references leads to noticeable compile time slow-downs for
non-OpenACC users of Graphite, the check can be re-introduced but
restricted to non-OpenACC functions.

gcc/ChangeLog:

	* graphite-scop-detection.cc (scop_detection::harmful_loop_in_region):
	Remove check for loops without data references.