[PlaceSafepoints] Cleanup InsertSafepointPoll function

While working on another change, I noticed that the naming in this function was mildly deceptive.  While fixing that, I took the oppurtunity to modernize some of the code.  NFC intended.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238252 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/IR/BasicBlock.h

@@ -116,6 +116,7 @@ public:
   ///
   /// Note: this is undefined behavior if the block does not have a parent.
   const Module *getModule() const;
+  Module *getModule();
 
   /// \brief Returns the terminator instruction if the block is well formed or
   /// null if the block is not well formed.

include/llvm/IR/Instruction.h

@@ -78,6 +78,7 @@ public:
   /// Note: this is undefined behavior if the instruction does not have a
   /// parent, or the parent basic block does not have a parent function.
   const Module *getModule() const;
+  Module *getModule();
 
   /// removeFromParent - This method unlinks 'this' from the containing basic
   /// block, but does not delete it.