[gn build] Port 106eb46

Author: aeubanks

llvm/utils/gn/secondary/llvm/lib/Target/AArch64/BUILD.gn

@@ -150,6 +150,7 @@ static_library("LLVMAArch64CodeGen") {
     "AArch64PBQPRegAlloc.cpp",
     "AArch64PointerAuth.cpp",
     "AArch64PostCoalescerPass.cpp",
+    "AArch64PrologueEpilogue.cpp",
     "AArch64PromoteConstant.cpp",
     "AArch64RedundantCopyElimination.cpp",
     "AArch64RegisterInfo.cpp",