This patch makes prune_runtime_alias_test_list take the iteration
factor as a poly_int and tracks polynomial offsets internally
as well.

2017-12-21  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

gcc/
	* tree-data-ref.h (prune_runtime_alias_test_list): Take the
	factor as a poly_uint64 rather than an unsigned HOST_WIDE_INT.
	* tree-data-ref.c (prune_runtime_alias_test_list): Likewise.
	Track polynomial offsets.

Co-Authored-By: Alan Hayward <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>

From-SVN: r255936