hypervisor: Add missing `const'.

sched_ctx_hypervisor/include/sched_ctx_hypervisor.h

@@ -150,7 +150,7 @@ double sched_ctx_hypervisor_get_elapsed_flops_per_sched_ctx(struct sched_ctx_wra
 
 double sched_ctx_hypervisor_get_total_elapsed_flops_per_sched_ctx(struct sched_ctx_wrapper* sc_w);
 
-char* sched_ctx_hypervisor_get_policy();
+const char* sched_ctx_hypervisor_get_policy();
 
 void sched_ctx_hypervisor_add_workers_to_sched_ctx(int* workers_to_add, unsigned nworkers_to_add, unsigned sched_ctx);
 

sched_ctx_hypervisor/src/sched_ctx_hypervisor.c

@@ -177,7 +177,7 @@ struct starpu_performance_counters* sched_ctx_hypervisor_init(struct hypervisor_
 	return perf_counters;
 }
 
-char* sched_ctx_hypervisor_get_policy()
+const char* sched_ctx_hypervisor_get_policy()
 {
 	return hypervisor.policy.name;
 }