[IPO] Remove a redundant cast (NFC) (#167832)

Idx is already of type unsigned.

Identified with readability-redundant-casting.

Author: kazutakahirata

llvm/lib/Transforms/IPO/IROutliner.cpp

@@ -2286,9 +2286,9 @@ void IROutliner::deduplicateExtractedSections(
     // Create a set of BasicBlocks, one for each return block, to hold the
     // needed store instructions.
     DenseMap<Value *, BasicBlock *> NewBBs;
-    createAndInsertBasicBlocks(
-        CurrentGroup.EndBBs, NewBBs, CurrentGroup.OutlinedFunction,
-        "output_block_" + Twine(static_cast<unsigned>(Idx)));
+    createAndInsertBasicBlocks(CurrentGroup.EndBBs, NewBBs,
+                               CurrentGroup.OutlinedFunction,
+                               "output_block_" + Twine(Idx));
     replaceArgumentUses(*CurrentOS, NewBBs, OutputMappings);
     alignOutputBlockWithAggFunc(CurrentGroup, *CurrentOS, NewBBs,
                                 CurrentGroup.EndBBs, OutputMappings,