[Statepoint] Improve two asserts, fix some style (NFC)

Summary:
It's important that our users immediately know what gc.safepoint_poll
is. Also fix the style of the declaration of CreateGCStatepoint, in
preparation for another change that will wrap it.

Reviewers: reames

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D7517

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228626 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/IR/IRBuilder.h

@@ -442,9 +442,9 @@ public:
   /// \brief Create a call to the experimental.gc.statepoint intrinsic to
   /// start a new statepoint sequence.
   CallInst *CreateGCStatepoint(Value *ActualCallee,
-                               ArrayRef<Value*> CallArgs,
-                               ArrayRef<Value*> DeoptArgs,
-                               ArrayRef<Value*> GCArgs,
+                               ArrayRef<Value *> CallArgs,
+                               ArrayRef<Value *> DeoptArgs,
+                               ArrayRef<Value *> GCArgs,
                                const Twine &Name = "");
 
   /// \brief Create a call to the experimental.gc.result intrinsic to extract