only declare activeDomainPoints in a single header

activeDomainPoints was declared in both schedule_tree.h and
schedule_transforms.h.  One declaration should suffice.
Other than activeDomainPoints, schedule_tree.h only has
the declaration of ScheduleTree itself, while all operations
are in schedule_transforms.h, so keep the declaration in
schedule_transforms.h.

Author: Sven Verdoolaege

tc/core/polyhedral/schedule_isl_conversion.cc

@@ -22,6 +22,7 @@
 #include "tc/external/isl.h"
 
 #include "tc/core/flags.h"
+#include "tc/core/polyhedral/schedule_transforms.h"
 #include "tc/external/isl.h"
 
 using namespace std;

tc/core/polyhedral/schedule_tree.h

@@ -514,10 +514,6 @@ struct ScheduleTree {
 };
 
 } // namespace detail
-
-isl::union_set activeDomainPoints(
-    const detail::ScheduleTree* root,
-    const detail::ScheduleTree* node);
 } // namespace polyhedral
 } // namespace tc