Type safe version of MachinePassRegistry

Previous version used type erasure through a `void* (*)()` pointer,
which triggered gcc warning and implied a lot of reinterpret_cast.

This version should make it harder to hit ourselves in the foot.

Differential revision: https://reviews.llvm.org/D54203

llvm-svn: 346522
diff --git a/llvm/lib/CodeGen/MachineScheduler.cpp b/llvm/lib/CodeGen/MachineScheduler.cpp
index 9ab405f..d4b9f85 100644
--- a/llvm/lib/CodeGen/MachineScheduler.cpp
+++ b/llvm/lib/CodeGen/MachineScheduler.cpp
@@ -240,7 +240,8 @@
   MachineFunctionPass::getAnalysisUsage(AU);
 }
 
-MachinePassRegistry MachineSchedRegistry::Registry;
+MachinePassRegistry<MachineSchedRegistry::ScheduleDAGCtor>
+    MachineSchedRegistry::Registry;
 
 /// A dummy default scheduler factory indicates whether the scheduler
 /// is overridden on the command line.