[Bug tree-optimization/66117] GCC can not compile when graphite is enabled, due to missing isl headers.

[pbeeler80 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66117

--- Comment #2 from Paul Beeler <pbeeler80 at gmail dot com> ---
A second shot at a patch:
Included HAVE_isl in gcc/graphite-poly.h
Other files that include "graphite-poly.h" will have isl_constraint functions
defined.
https://github.com/SaberMod/GCC_SaberMod/commit/3494aee764bb64948d6cd2f2c430cfc8e69ba078