Automerge: [gn build] Port de209fa

Author: llvmgnsyncbot

llvm/utils/gn/secondary/llvm/lib/CodeGen/BUILD.gn

@@ -228,6 +228,7 @@ static_library("CodeGen") {
     "StackMaps.cpp",
     "StackProtector.cpp",
     "StackSlotColoring.cpp",
+    "StaticDataSplitter.cpp",
     "SwiftErrorValueTracking.cpp",
     "SwitchLoweringUtils.cpp",
     "TailDuplication.cpp",