scheduler.c: use isl_bool enum instead of plain integers
scheduler.c: use isl_bool enum instead of plain integers

This improves readability of the code and helps bug-finding tools,
which warn on integer to enum conversions in C.

Signed-off-by: Tobias Grosser <059b8b880f8441509ec8a65b50b4c6ae74ebea76@grosser.es>
Signed-off-by: Sven Verdoolaege <235c10dd23b819f81cdc9756a251746bc184cab6@gmail.com>

Meinersbur/isl,inducer/isl-mirror,PollyLabs/isl,inducer/isl-mirror,PollyLabs/isl,inducer/isl-mirror,Meinersbur/isl,PollyLabs/isl,PollyLabs/isl,inducer/isl-mirror,Meinersbur/isl,Meinersbur/isl,inducer/isl-mirror,PollyLabs/isl