[gn build] Port af6fa77

Author: llvmgnsyncbot

llvm/utils/gn/secondary/llvm/lib/Target/AMDGPU/BUILD.gn

@@ -137,6 +137,7 @@ static_library("LLVMAMDGPUCodeGen") {
     "AMDGPUAsmPrinter.cpp",
     "AMDGPUAtomicOptimizer.cpp",
     "AMDGPUAttributor.cpp",
+    "AMDGPUBarrierLatency.cpp",
     "AMDGPUCallLowering.cpp",
     "AMDGPUCodeGenPrepare.cpp",
     "AMDGPUCombinerHelper.cpp",