[gn build] Port 518292d

Author: llvmgnsyncbot

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

@@ -59,6 +59,7 @@ static_library("LLVMPowerPCCodeGen") {
     "PPCMIPeephole.cpp",
     "PPCMachineFunctionInfo.cpp",
     "PPCMachineScheduler.cpp",
+    "PPCMacroFusion.cpp",
     "PPCPreEmitPeephole.cpp",
     "PPCQPXLoadSplat.cpp",
     "PPCReduceCRLogicals.cpp",