[gn build] Port 22a1aa5a43

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

@@ -2,6 +2,7 @@ static_library("Demangle") {
   output_name = "LLVMDemangle"
 
   sources = [
+    "DLangDemangle.cpp",
     "Demangle.cpp",
     "ItaniumDemangle.cpp",
     "MicrosoftDemangle.cpp",

llvm/utils/gn/secondary/llvm/unittests/Demangle/BUILD.gn

@@ -3,6 +3,7 @@ import("//llvm/utils/unittest/unittest.gni")
 unittest("DemangleTests") {
   deps = [ "//llvm/lib/Demangle" ]
   sources = [
+    "DLangDemangleTest.cpp",
     "DemangleTest.cpp",
     "ItaniumDemangleTest.cpp",
     "OutputBufferTest.cpp",