Change includes to support new slicer header location

This should prevent any future issues with header or macro name
collisions.

Also remove the pragmas for undefining the CHECK macro since we
renamed the incompatible slicer version.

Warning pragmas are still required.

Bug: 65422458
Test: ./test.py --host --redefine-stress
Change-Id: I076302743163e08a9b16f44fb894f5d96b38712e