[RS4GC] Remove a redundant linear search, NFCI

Since LiveVariables is uniqued (we just created it from a `DenseSet`),
`FindIndex(LiveVariables, LiveVariables[i])` is always `i`.

llvm-svn: 250786
diff --git a/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp b/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
index 2001b07..6be71dc 100644
--- a/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
+++ b/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
@@ -1342,8 +1342,7 @@
     // Generate the gc.relocate call and save the result
     Value *BaseIdx =
       Builder.getInt32(LiveStart + FindIndex(LiveVariables, BasePtrs[i]));
-    Value *LiveIdx =
-      Builder.getInt32(LiveStart + FindIndex(LiveVariables, LiveVariables[i]));
+    Value *LiveIdx = Builder.getInt32(LiveStart + i);
 
     // only specify a debug name if we can give a useful one
     CallInst *Reloc = Builder.CreateCall(